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 calf leather
Padded design for extra comfortability 
Stitched construction
Strap thickness: 3.5mm
Stainless steel butterfly deployant clasp

38/40/41mm: Length: 75mm and 120mm
42/44/45/49mm: Length: 75mm and 120mm

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