The router mill tool holder portion of the 80% lower jig tool is super-heated to accept our custom 5/16" diameter end mill, which has been optimized in every facet for 80% lower milling. The end mill being thermal fit into the tool holder means it will never slip out during use. However, the end mill tool portion of the ReadyMILL™ is replaceable by the end user at a much reduced cost to previous end mill designs.
The length of the end mill portion of the ReadyMILL™ by 5D Tactical has been reduced to only 1.5 inches! This is less than half the length of any other end mill bits available for router based 80% lower milling. All of this adds up to a strong and super-rigid milling tool that virtually eliminates tool chatter and produces mirror-like finished results in less time than ever before.

Use the guide below to determine the correct ReadyMILL™ size for your router. Your router's model number can be found on the label. Generally, most routers using the size D will require the full-size router plated located here to work

If you have a router not listed, you can reference the below sizing and thread pitch, and see which would match up with your router's spindle. It can be tricky to get these measurements, and for more information on collecting the info, you can visit:
https://www.fastenermart.com/understanding-metric-fasteners.html