Head circumference and size Head circumference suitable range: 5264 cm (20.025.0 inches). Overall size: 16 cm x 20 cm wide. Includes 2 sets of helmet connectors for flexible mounting with compatible head protection systems. Compatible with helmets such as FAST, MICH, and similar models. Design and wearing options Design 1: Elastic headband is adjustable to fit your face, providing a secure and comfortable fit with good ventilation for extended use in airsoft and related activities. Design 2: Lens system includes 3 lenses (gray, transparent, and yellow) that can be swapped for different environments. Comfort features: The goggles include a sponge (foam) inside for comfortable wear during long sessions. Wearing modes: Mode A: Headwear mode using the elastic headband. Mode B: Helmet wear mode using 2 helmet adapters for connecting helmet side rails. Protection and performance Strong impact resistance: ANSI Z80.3 falling ball test compliant. Temperature tolerance: Functions effectively from 10 degrees Celsius to 42 degrees Celsius. Velocity protection: Impact resistance up to 310 fps. Use scenarios Airsoft games: Provides eye and head protection with adaptable lens options and helmet mounting capability for increased versatility on the field. Tactical training and milsim events: Offers secure fit, interchangeable lenses, and helmet compatibility for realistic exercise setups. Outdoor or security drills: Suitable for environments requiring reliable eye protection with the option to mount with compatible helmets. Key attributes at a glance Function: Eye protection with helmetmount capability, adjustable fit, and swapable lenses. Compatibility: 2 helmet adapters for side rails; works with FAST, MICH, and similar helmets. Size and fit: 5264 cm head circumference; 16 cm H x 20 cm W frame. Materials and comfort: Elastic headband; foam/sponge padding inside for comfort. Performance: ANSI Z80.3 rated; 10 to 42 C operating range; up to 310 fps impact resistance.