Klein Tools Heavy-Duty Nut Driver

No. The Klein Tools 635 heavy-duty nut driver is not insulated and will not protect against electrical shock, so it must not be used on energized conductors or terminals. De-energize and verify dead first, and wear approved eye protection. If you need to work live, you need a rated insulated (1000V) driver instead.

Yes. The 635 has a hollow shaft, so the bolt passes up inside it and there is no limit on bolt length. That is the difference between this and a solid-shaft nut driver or a socket on a stubby handle, which bottoms out once the stud protrudes past the socket depth. Shaft length is 4 inches (10.2 cm), so that is your working reach down into a box or panel.

Five hex sizes: 5/16, 3/8, 7/16, 1/2 and 9/16 inch, ordered as 635-5/16, 635-3/8, 635-7/16, 635-1/2 and 635-9/16. Each size is color coded on the handle so techs can grab the right one out of a pouch without checking the stamp, which is why crews often buy the run rather than a single size.

It does. The 635 is magnetic, which retains the nut in the socket while you get it started, useful on overhead strut, panel covers and machine screws with hex heads where you have one hand on the ladder. The magnet holds steel nuts; brass or stainless hardware will not stick.

Yes, the 635 has a wrench assist built into the handle so you can apply a wrench for extra torque when a nut is tight or seized. Handle dimensions are 1.35 by 2.34 inches. Use judgement on how hard you lever it, and back off if the nut is galled rather than shearing the stud.

For repetitive small hex work in a panel, the 635 nut driver is faster: one tool, a Cushion-Grip handle you can spin with your fingers, a magnet that holds the nut, and a hollow 4 inch shaft that runs down a long stud a ratchet socket cannot clear. Go to a ratchet when you need real breakaway torque or a deep offset. The 635 splits the difference with its wrench assist for the occasional tight one.

Steel shaft with the classic Klein Cushion-Grip handle. It is described as a heavy-duty shaft, which is what lets it take the wrench assist without twisting.