I'm surprised Moderators here don't have access to IP addresses, I was a Moderator on another site, and member's IP addresses always appeared under the users member name. but I'll say that the OP should get a 1/4" collet rather than bother with an unsafe, and very thin, bushing only a few thousandths thick!..Bob I'm suspecting that you may not be in North America. This is why we need members to fill out their personal profile because not being in NA makes a big difference in what we suggest to you. I'm guessing that that may be an 8mm collet which is common on European routers. I heard talk at one time that 1/4" shank bits were going to be gradually phased out here but it hasn't happened yet.