Super-O Boyer watch bracelet is composed of 3 flat and solid 316L stainless steel units and a curved solid end piece perfectly fit Seiko MM300 Prospex Marinemaster SBDX001/SBDX003/SBDX005/SBDX017 models. Screw-in adjustable details instead of pressure pins. This item includes one pair of FAT spring bar (eg. generic Seiko Dia. 2.5mm spring bar) to ensure a more secure connection. Tapered 20mm lug into 18mm buckle size. Accompanied with brand new SUB double locks diver's clasp, made from solid 316L stainless steel with extra 6 micro holes for flexible fine tune length adjustment. SUB double locks diver's buckle is ideal for watch band with thickness approximate 4.0 - 5.0mm. Super-O Boyer watch bracelet is a good choice of Seiko replacement watch band for your MM300 Prospex Marinemaster SBDX001/SBDX003/SBDX005/SBDX017 models.