Super Engineer II watch bracelet is designing for 2009 onward Seiko Tuna models such as SBBN013 or other 21.5mm lug Seiko diver or sport watch case with straight lug. Super Engineer watch bracelet is an extraordinary well made 316L stainless steel watch band. Each links are composed of 5 Chamfer edge solid 316L stainless steel units are assembled with screws instead of flimsy pins to keep its solidity and stability. Length adjustment is simple & easy via flexible screw details. Item also included one pair of FAT spring bar (eg. generic Seiko Dia. 2.5mm spring bar) to ensure the watch band is connected securely with your watch. Today replaces your Seiko Tuna into this unique aftermarket watch bracelet.