[radios]

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.

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!..