Megapro 15 in 1 ShaftLOK Driver has an unique locking mechanism on the shaft. The locking shaft eliminates the hassle of bits falling out of the shaft when getting partially “stuck” in the fastener as the driver is pulled back away from the fastener. LOCK the bit in place by pushing it completely into the shaft until it “clicks” locked. To UNLOCK the bit by pushing down on the yellow button on the shaft and pulling out the bit. Bit load contain double ended bits, Phillips 1-2, Phillips 0-3, Square 0-3, Square 1-2, Flat(slotted) 4-6, Torx 10-15, Torx 20-25. And the shaft opening serves as a 1/4″ hex nut driver.