Natural resin strap, moderate hardness, sturdy and durable. Compatible with PRG-110C, PRG-110Y, PRW-1300, PAW-1300 and other models, not suitable for other models. Please make sure your watch model is listed in the description before purchasing, If not, please contact customer service 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.