This is a good reliable impact adapter set that fits standard size 1/4", 3/8 "actuators and discs 1 is suitable /2". The plastic holder is pretty basic and I had to use a flathead screwdriver to wedge in a couple of adapters because the plastic part of the holder was a bit too big, but after I cut some of the plastic with a sharp knife the adapters stood up and came off. much easier. This is a staple in any toolbox and a good value. Ball bearings fit well with enough spring tension to properly hold each clutch.