Overstitcher and Pricking Wheels

Overstitchers 

Overstitch wheels are used to make spacing marks to aid in even hand-stitching and then to roll over the finished stitches to help "set" them. They have a rounded profile between the points to round up the stitch appearance as well. 

Gomph Overstitchers

HF Osborne Overstitchers

CS Osborne Overstitchers

Other Maker Overstitchers

Pricking Wheels

Pricking wheels are also used to make spacing marks for hand-sewing. Generally speaking the points are a little sharper and more distinct than an overstitching wheel. Many who hand sew prefer a pricking wheel for that reason.