Nice very low runout collet at a reasonable price. Good quality.
This is a nice ER-20 collet with great run out. The runout is on the same order as my spindle and if I experiment a little, I can get the two to nearly cancel and get runouts near 1 tenth. I'm a home shop Machinist and have a mish mash of ER-20's. My 4 station tool changer uses a ER-20 holder and these collets hold my best finishing tools. Some of my collets are as bad as 2 thou and not repeatable. Worth a few extra bucks. ER-20 is not a very standard size in the world of ER collets. If you're starting out and have a choice, go with 16 or 30, much more standard.