We've had many requests for a small dovetail cutter that would speed up the cutting of dovetails in front sight blades when installing colored inserts. The one we've had made cuts a ¼" wide dovetail, just right for sight inserts, and the finished product is very precise. Since the cutter is small, (it tapers to a diameter of .110"), you must make an initial cut with a 1/8" end mill. By using the end mill to remove some metal first, you'll avoid overloading the cutter and breaking it. CAUTION: For use in milling machine only. High speed steel. 21⁄32" (5.1cm) long. 1⁄4" (6.3cm) diameter shank. Maximum cut depth is .100" (2.5mm) 60° shoulder. DO NOT EXCEED 700 rpm, HIGHER SPEED WILL BREAK TEETH.