HD, 9H, 91.5%, 45°, 48H, 0.13mm - a plain-English guide to every number on the box.

Screen protector packaging is full of numbers and labels. HD. Anti-blue ray. 9H hardness. Self-healing. 45-degree privacy. UV curing. 0.13mm thickness.

Most of these are real specifications that describe real differences in performance. But without context, they are just marketing text.

This guide takes each major spec and explains what it actually means in daily use - so the next time you are choosing a film, you know exactly what you are paying for.

Light Transmissivity: Why >91.5% Matters

Transmissivity measures how much light passes through the film before reaching your eyes. A higher percentage means a clearer, brighter image.

A bare phone screen typically transmits close to 100% of its own light output. Every layer you add between the screen and your eyes reduces that figure slightly.

Standard films on the market often sit between 85% and 90% transmissivity. At these levels, most users notice a slight dimming or softening of the display, particularly in direct sunlight.

Films rated at above 91.5% transmissivity - such as the Purcell F-series 4K HD films - are engineered to stay close to the original screen experience. The difference is most noticeable on high-resolution displays and OLED screens, where color accuracy and brightness are core to the design of the device.

If you have a premium display, the transmissivity spec is not a minor detail. It is the number that tells you whether your screen protection will preserve what you paid for.

Film Thickness: 0.13mm vs 0.4mm - What Is the Difference?

When a film is described as 0.4mm total thickness, that includes all layers stacked together: the outer protective coating, the functional film itself, the adhesive layer, and the backing that gets peeled off before application.

The number that actually matters for feel and performance is the used thickness - the layer that remains on your screen after the backing is removed. For Purcell hydrogel films, this sits at 0.13 to 0.15mm.

At that thickness, the film is thin enough that touch response is not affected. There is no noticeable gap between your fingertip and the display surface. For gaming, typing, or anything requiring fast and precise input, used thickness is the spec to check.

Thicker films - particularly some tempered glass options - can create a measurable lag in touch sensitivity, especially toward the screen edges. Hydrogel films at 0.13 to 0.15mm do not have this problem.

The Four-Layer Structure: What Each Layer Does

Quality hydrogel films are built in four distinct layers, each with a specific function.

The outermost layer is a protective coating applied before use. It keeps the film surface clean during shipping and handling and is removed just before installation.

The used layer is the functional film itself - the part that adheres to your screen. This is the TPU or hydrogel material that provides protection, clarity, and any special coating (matte, anti-blue, privacy, etc.).

The release layer sits beneath the used layer and separates it from the bottom backing. It allows the adhesive to stay clean until the moment of application.

The bottom layer is the final backing that gets peeled away last, exposing the adhesive surface for application.

Why does this matter? Because a poorly constructed film - or a cheap alternative that skips layers or uses inferior materials at any stage - will show it in adhesion quality, bubble formation, and edge behavior within days of application.

Privacy Film: What Does 45 Degrees Actually Block?

Privacy films are designed to block the view of your screen from anyone not looking at it directly. The key spec is the viewing angle - the point at which the screen becomes unreadable to an observer.

A 45-degree privacy film means that anyone viewing from more than 45 degrees to the side of the screen sees a black or near-black display. Only the person directly in front of the phone can read the content.

Purcell privacy films use LG anti-peep optical material from South Korea, which achieves this 45-degree cutoff while maintaining HD transparency for the direct viewer. This is an important distinction - cheaper privacy films often reduce clarity noticeably even for the user looking straight at the screen.

A privacy film that protects your screen but makes everything look dim and yellow is not a practical solution for daily use. The optical quality of the base material determines whether you get genuine privacy without compromising your own viewing experience.

Self-Healing: What 48 Hours Really Means

Self-healing is one of the most misunderstood specs on screen protector packaging.

It does not mean the film repairs itself after a drop, a crack, or a deep gouge. It means that minor surface micro-scratches - the kind caused by light contact with clothing, soft surfaces, or dust - can close over time as the film material relaxes back to its original shape.

Purcell films using synthetic optical memory crystal material with micro crystal slow rebound technology can repair these surface marks within 48 hours under normal conditions. The process works because the film material has elastic memory - it returns toward its original flat state after minor deformation.

The practical benefit is that the film stays visually clean for longer. A film without self-healing properties accumulates surface micro-scratches visibly within weeks of use, even with careful handling. A self-healing film extends the period during which the surface looks and feels new.

What self-healing cannot do: repair scratches that penetrate through the surface layer, or reverse damage from hard impacts. For those scenarios, the film has served its purpose and needs replacement. For a guide on when exactly to replace your film, see How Do You Know It's Time to Replace Your Screen Protector?

99.99% Antibacterial: What Is Being Measured?

The antibacterial specification refers to the film's effectiveness at reducing bacterial growth on its surface over a defined period.

A 99.99% antibacterial rating means that the surface treatment reduces the presence of common bacteria strains by 99.99% within the tested timeframe. Purcell antibacterial films maintain this level for 24 hours of continuous protection.

Phone screens are high-contact surfaces. Research consistently shows that phone screens carry more bacteria per square centimeter than most household surfaces that people consider dirty. For users who are health-conscious, work in medical or food environments, or share devices, an antibacterial coating is a meaningful functional specification - not a marketing claim.

The 24-hour durability means the coating remains effective through a full day of normal use, including cleaning and contact with hands and surfaces.

UV-Cured Films: What Does 80% Stronger Actually Mean?

UV-cured films represent a different category from standard hydrogel or TPU films. They use a UV optical adhesive that bonds the film to the screen surface through a curing process, rather than relying on dry adhesion alone.

The result is a full-surface bond - the adhesive covers the entire screen area with no air gap, which means the display retains its original brightness and color without any interference from air pockets.

The 80% increase in resistance strength referenced for Purcell UV films refers to the impact resistance of the combined system - film plus UV-cured adhesive plus screen - compared to a non-bonded film of equivalent material. The full adhesion means the film acts as part of the screen structure rather than a separate layer resting on top.

The tradeoff is the installation process. UV films require a UV curing lamp and a slightly more involved application step. They are better suited to professional installation than self-application. For shops offering a premium tier service, UV film installation is a clear differentiator - the result is a level of optical and structural performance that no peel-and-stick film can match.

Anti-Blue Ray: What Is Actually Being Filtered?

Blue light is the portion of the visible light spectrum in the 380 to 500 nanometer range. Modern smartphone displays - particularly OLED and high-brightness LCD panels - emit significant amounts of blue light as part of their normal operation.

Anti-blue ray films filter a portion of this spectrum before it reaches the eye. The practical effects most commonly reported by users are reduced eye fatigue during extended use, reduced difficulty falling asleep after nighttime phone use, and reduced dry or irritated eyes.

The Purcell F300B and F500B anti-blue ray films are designed to filter harmful blue light while preserving as much color accuracy as possible. This is the key engineering challenge in anti-blue ray film design - filtering enough blue to reduce strain without shifting the display toward a yellow or orange tone that distorts colors and makes the screen unpleasant to use.

If you use your phone for two or more hours daily, regularly check it before sleeping, or work from your phone for extended periods, an anti-blue ray film addresses a real and measurable source of visual fatigue.

Reading the Box: A Quick Reference

Transmissivity >91.5% - how much of the screen's light reaches your eyes. Higher is clearer and closer to the original display.

Used thickness 0.13 to 0.15mm - the layer that stays on your screen. Thin enough that touch response and display feel are unaffected.

Four-layer structure - indicates quality construction. Each layer has a function. Fewer layers or lower-grade materials show up as adhesion problems and early failure.

45-degree privacy angle - the point at which the screen becomes unreadable from the side. Measured with LG optical material for color accuracy at the direct viewing angle.

48-hour self-healing - surface micro-scratches close within 48 hours. Does not apply to deep cuts or impact damage.

99.99% antibacterial, 24-hour - bacterial reduction on the film surface for a full day of use.

UV curing, +80% impact resistance - full-surface adhesive bond through UV curing. Higher structural integrity, professional installation recommended.

Anti-blue ray - filters the 380–500nm blue light spectrum. Reduces eye fatigue and sleep disruption from extended screen use.

Further Reading

Not sure which film material is right for your device? See our breakdown:

TPU vs. EPU vs. PET: What You Can't Afford to Ignore When Choosing Screen Protection Materials

Already using a film and wondering if it's time to change it? Read:

How Do You Know It's Time to Replace Your Screen Protector?

Purcell's front film range covers HD, anti-blue ray, matte, privacy, self-healing, antibacterial, and UV-cured options - all compatible with Purcell intelligent cutting machines for on-demand precision cutting at point of sale. Browse the full Purcell film range or contact the team to discuss your requirements.