Since the back is transparent

Blade thickness 3mm

but what is called a "leather look"

Chopstics Rest      　 10mm x 50mm

"BANTO" Replacement Japanese Carbon Blade 35mm for Multi-brand Hand Plane Leather Case Since the back is transparent"BANTO" Replacement Japanese Carbon Blade 35mm for Multi brand Hand Plane Three HONMAMON Stars (link) While most Western plane blades are made from a single piece of steel, our replacement blades are produced by a Miki based plane blacksmith using the same laminated construction as Japanese kanna bladesBlue Paper Steel No. 1 forge welded to soft iron. This results in noticeably superior sharpness and ease of sharpening. Drawing on traditional Japanese