I was initially to receive this set of screwdrivers. As a band director, I'm constantly repairing instruments that have flat head screws. However, on my very first use, the blade of the screwdriver slipped out of the handle. I put it back in, tightened the fastening screw, and retried. To my surprise, this happened several more times despite repeated fastenings of the screw holding the blade in. I gave up, put the screwdrivers back in the box, and sent them back to amazon.