Durable PC construction for long lasting use Three buckle system design: the middle is a fixed four fold buckle, with grooves on both sides for the four fold buckles. The four fold buckles on both sides can slide, with a sliding space of about 3 cm. Up design with ratchet: both sides are fixed by a ratchet to prevent the buckle from dropping easily. Wide compatibility: suitable for helmets with three buckles, as well as various half helmets and 3/4 helmets. Key benefits Secure closure: ratchet mechanism helps keep the buckle in place and prevents accidental release. Adjustable fit: sliding capability of about 3 cm allows for a comfortable fit across different head sizes and helmet styles. Durable and lightweight: made from polycarbonate (PC) for strength and long service life without unnecessary weight. Versatile compatibility: designed to work with helmets that have three buckles, including many half and 3/4 helmet models. Use scenarios Replacing worn or damaged buckles on a threebuckle helmet to restore secure closure and fit. Upgrading an older half helmet or 3/4 helmet to improve stability and adjustability without changing the helmet shell. Using across different helmet styles (threebuckle systems, various half helmets, and 3/4 helmets) to ensure reliable closure during daily commuting, city riding, or recreational riding.