Attachment 41432I received a drill bit kit - many assorted sizes and types with a few extras like a hole saw and some grinding wheels but basically a drill bit kit. In it are 2 - exactly the same - grey things that look like Marr connectors but aren't. They are about that size but (a) have a hole at each end - roughly 7/16" and 3/8" and (b) have a springy thing inside with 6 "teeth". Thought they might be drill bit stops but no, and they are not adjustable in any manner. You can stick a drill shank into it and the "teeth" may catch or scrape on the shank but that's about it. I've asked elderly men -retired guys who should know things like this - working at the local Home Hardware but no one knows what they are for. Anybody?