I have a syl x5 speedmaster, it comes with er11 collets. It would be nice if I could use bits a little larger than 7mm shaft, but more than that I would sure like to be able to change my bits much faster. It can take several minutes to change a bit, trying to balance 2 wrenches at a time and hold a bit from falling out, drives me crazy. Then to change a collet, you have to take the nut off then find something to push the collet out of the nut. It's a reliable system, but not friendly.