Double Lock has 3 options to choose from, all are corrosion resistant Brass
2 x holes (total locking via two holes)
1 x hole (use one thumb to release the driver quick change)
0 x buttons (simple push on and slide off, not used in down flue work)
All drivers have a hard wearing stainless steel shaped driver (crimped pinned and glued into the brass fitting) Driver fits round chucks and 3 jaw chucks to eliminate slippage and chuck wear from slippage.