Imagine you want to spend a grinding disc (3.2mm) to make a hole of 1 mm, it is necessary to unscrew the head completely, change the clamp screw completely. Ben there, done! you use this chuck like a drill. I had a slight doubt about concentricity, but nay! it turns perfectly round, and the accessory change is fingertip: more key! Frankly, for the price, it's worth it ...
