This nut driver is super handy to have when building with M4 hardware. It has a long end and a short end; both 7mm hex. The long end has a deep counterbore beyond the hex drive so that you can drive a nut even if the threads of the bolt (or threaded rod) protrude beyond the top edge of the nut. To gain leverage you can use the short end of the driver. It has a thru-hole beyond the hex drive so you have no limitation on how far past the nut the threads protrude. Because this end of the driver is under 11mm in overall diameter, there’s clearance to use this on nuts that are near the wall of 1120 and 1121 Channel.