I bought this to make it possible to remove those impossible-to-remove fasteners that are usually rusted in place. An electric or pneumatic impact driver is critically different from this in that those drivers impact fasteners in a radial action only--they are good for tight fasteners, but not as much for the most rusted and stuck fasteners. This device has the rotating action combined with the hammering action that presses the bit into the fastener, meaning that this impact driver is less likely to slip as it makes each impact. The bits in this set all seem quite well made. I think the most useful bits will be the Philips and Slotted, since those are always the easiest to slip and strip with a screwdriver. The only thing I wish were included in this box is a 1/2" square to 1/4" hex adapter for 1/4" bits. The set includes a 1/2"-5/16" adapter for larger bits, but the 1/4" bits are more common and easier to replace. I might purchase the other adapter to use it with my other impact bits as needed.