There is a good reason almost all drill bits are single sided. These reversible bits keep jamming in what I consider normal use. The knurled end (T-24) is not strong enough to withstand the compressive forces inside the bit holder. Usually the end of the beat is distorted and then stuck in the percussion instrument rather than ejected. In order to then remove the bit, it is necessary to fix the rider's collar in the open position with a wire or cable tie and clamp the bit squarely with the locking pliers. If you stand on the pliers and pull the screwdriver at the same time, you will loosen the bit. Too much effort for zero benefit. I recommend you skip this product.