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Every sunglass lens sold in a regulated market carries a tint category—a number from 0 to 4 that defines how much visible light passes through the lens and, in turn, which environments the product is legally approved for use in. This single specification determines product liability exposure in the EU, drives labeling requirements in Australia, and governs whether your lens can be marketed as suitable for driving in the UK or Germany.

For OEM eyewear buyers, brand owners, and optical retailers, understanding tint categories is not optional. It is the foundation on which product specification, compliance documentation, and market positioning are built. Specifying the wrong category for a target market does not produce a minor regulatory inconvenience — it produces a product recall, a customs rejection, or a product liability claim.

This guide defines each of the five tint categories under EN ISO 12312-1, explains how visible light transmittance (VLT) is measured and what it determines, covers the specific compliance implications for key export markets, and provides a complete OEM specification and sourcing reference for brands building sunglasses at volume.

This guide covers the technology, OEM customization options, and sourcing criteria that determine photochromic lens quality—structured to help buyers match product specifications to their target markets and distribution channels.

This guide walks through everything a serious buyer, brand owner, or optical retailer needs to know: core optics, the three mainstream production processes Karuson deploys, material trade-offs between CR-39 and Polycarbonate, coating architecture, and a practical tint-selection guide — all grounded in ISO 12312-1 compliance.

Standard polarized lenses that pass EN ISO 12312-1 can still fail in marine environments — not because of the polarization layer, but because of the coating system underneath it. This guide explains exactly why: how Cl⁻ ions migrate through standard Si-based hard coats, reach the coating-substrate interface, and initiate delamination within 180–240 days of saltwater exposure. It covers the full 4-layer anti-seawater coating stack (salt-resistant Si-organic hybrid base through oleophobic top coat), ISO 9227 96-hour salt spray performance targets, and the construction differences between TAC lamination and CR-39 cast-in polarization for marine use. Tint category specifications for inshore fishing, offshore sailing, and high-glare conditions are included, along with a complete OEM sourcing checklist and production specs from MOQ 300 units.

CR-39 and polycarbonate are the two most widely used lens materials in OEM sunglasses and optical eyewear production. They are not interchangeable. Each has a specific optical profile, impact performance, and processing requirement that maps to a defined set of product categories. Selecting the wrong material for the wrong application does not produce a slightly inferior product — it produces a structurally mismatched one. This guide provides the technical basis for making that decision correctly.

If you're sourcing custom sports sunglasses—whether for a cycling brand, an outdoor retail chain, or a private-label fitness line—frame material is one of the first decisions that shapes everything downstream: price point, target audience, tooling complexity, and the story your product tells on shelf. As a lens manufacturer working with OEM and ODM partners worldwide, we're often asked the same question: which material is right for my product? This guide breaks it down clearly so you can walk into your next sourcing conversation with confidence.

Discover the differences between OEM and ODM partnerships for your eyewear business with KARUSON, a leading custom sunglasses manufacturer. Learn which model suits KARUSON goals best to create unique, high-quality eyewear that stands out in the market. Choose KARUSON for expert guidance.

Discover why global brands choose KARUSON, a leading China eyewear factory, for quality, innovation, and cost-effective sourcing. Partner with us to elevate your eyewear collection with reliable manufacturing and strategic advantages. Trust KARUSON for your global eyewear needs.

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