This Super-J Louis watch band with a curved solid end pieces perfectly fit Seiko 63Mas - Seiko Prospex SPB143, SPB145, SPB147, SPB149 with Dia. 40.5mm, the interpretations of Seiko's First 62MAS models. New Super-J Louis watch band is more than an upgraded version of vintage J Louis watch band. Curved end link was shaped more tangible by applying an advanced crafting technique. The improvement on 3-dimensional effect curved solid end piece is highly visible. All solid links including end links are structured by screw fix adjustable details instead of common pins. (Compatible with original Seiko 18mm buckle, if you want to install your original Seiko clasp, please checks the size of your Seiko clasp first.) This item includes one pair of FAT spring bar (Generic Seiko Dia. 2.0mm spring bar) to ensure a more secure connection. Accompany with V-Clasp double lock buttoned diver's clasp. V-Clasp was made from solid 316L stainless steel with extra 6 micro holes for flexible fine tune length adjustment. Featured in V shape safety lock, streamlined form & chamfer edged design to giving a more massive look. Chamfer double locks diver's buckle is ideal for watch band with thickness approximate 4.0 - 5.0mm thickness. Another awesome aftermarket stainless steel watch band for 63MAS Dia. 40.5, 62MAS-inspired Prospex SPB line 200m models. Today replace your Seiko watch into this unique aftermarket bracelet.