I am a do-it-yourselfer and am using a countersink for the first time. The packaging could be better. The packaging with the lock deteriorates after a few uses. More importantly, the smaller bits should have a smaller countersink, they are all almost the same size. This can result in the cross sections getting wider and deeper than you'd like. The bits are the same, they are not narrow at the top like big brands. So if you care about them, this may not be for you. Great for DIYers. Excellent value for money for sure.