Natural Resin material, safe and assured, Compatible with Casio AE-1000W / AE-1300 / AE-1200 /SGW-300H / SGW-400H / SGW-500H /AQ-S810 / AQ-S810W / AQ-S800W / W-S200H / W-800H / W-216H / W-735H / F-108WH / W-215 / AEQ-1100 model watch band（the interface size is 18mm (0.7") Please make sure your watch model is listed in the description before purchasing, if not, use a metric ruler to measure the lug width or the width of the current strap connection （18mm (0.7")）.To save your precious time and effort, and avoid the hassle of returns and exchanges, choose the correct size for your watch. It is very important to be accurate to the millimeter