Saw a show once about old mills, they used something very similar to sew bags closed. I don-t think its for leather- the foot for withdrawl of the needle means it most likely isn't for lighter weights of hide, the bend innthe handle would severly limit the leverage applied to push through- nor would it be ergonomic for a clamp style work. The thread guide is interesting. Looks like a fun apeciality tool, but I think leather is the weong world to look at. Any marks?