This Schrillo 6300 Large Microstop Countersink 3/8-24-THD is an essential tool for any aircraft mechanic or metalworker. It is a brand new old stock item that has never been used.  Crafted with precision, this countersink is ideal for drilling and countersinking holes in metal and other materials. Its counterbore diameter of 3/8 inches and its model number 6300 make it a versatile tool that can be used in a variety of applications. A must-have for anyone in the CNC, metalworking, or manufacturing industry, this Schrillo countersink is a reliable and efficient tool that will help you get the job done quickly and accurately.