Very good key with a length of 110 mm for the 6 mm universal chuck for comfortable tightening/loosening of the 13 mm chuck in 1/2 unf or in 3/8 and in S2 quality. If you don't want the round shafts to slip on your drill, then mechanical chucks with a good chuck/key like this one from BOSCH are the way to go. The (automatic) ones are only for hex and occasionally for use with a round shaft. It's a shame that now all drills come with (automatic) chucks which ALL SLIP, and I have replaced them with mechanical ones directly. (I have about 8 different and very expensive drills.)