Peripheral Drive System. • 6mm Hex Drive Quick Release Bit Coupler (65mm). Hex: 1.5mm, 2mm, 2.5mm, 3mm, 4mm, 5mm, 6mm. 6 positive stop position hex sockets. All LOK-ON™ Socket Sets include industry leading and highest quality custom EVA foam trays that includes a hard shell surface with clearly marked sizing.