Fits Apple watch size 38mm (Series 1,2,3), 40mm (Series 4,5,6,SE), 41mm (Series 7)
Fits Apple watch size 42mm (Series 1,2,3), 44mm (Series 4,5,6,SE), 45mm (Series 7,8), 49mm (Ultra)

Made from genuine oil waxed calf leather
Two-point stitched design
Strap thickness: 2.5mm
Stainless Steel Buckle

38/40/41mm: Length: 75mm and 125mm
42/44/45/49mm: Length: 80mm and 125mm

Product showcase video for the Premium Vintage Leather Strap can be found 

Video tutorial on how to change the strap for Apple Watch can be found