The Crafter Blue CB11 curved end rubber strap is originally engineered for Seiko SKX007, SKX009, and SKX011 models, etc. However, it can be compatible with the 42.5mm Seiko 5 Sports SRPD series (the SKX replacement). Crafter Blue CB11 rubber band is made of pure vulcanized rubber which has superior strength and is more resistant than natural rubber to oils and acids. Material has also met the RoHS requirements and rarely causes severe allergic reactions. Accompany with well-built stainless steel buckle and a featured big keeper. Accompany with well-built stainless steel buckle and a featured big keeper. It also includes a pair of replacement spring bars for easy installation.