Durable Premium Brass Shock-Proof UV Filter, designed for optimal lens protection in harsh environments Constructed with high-quality Schott B270 glass for superior light transmission and hardness Features a 3.1mm ultra-thin frame design with knurling for easy grip Unique 36-layer coating (18 layers on both sides) for maximum light transmission up to 99.4% Provides enhanced image clarity and sharpness, improving overall photography results Double-sided waterproof & oil-proof for robust protection & longevity in all weather conditions