Klein Tools 646-INS Insulated Nut Driver, 6-Inch Hollow Shaft

Yes. The 646-INS nut drivers are individually tested to exceed IEC 60900 and ASTM F1505 for insulated hand tools and carry the official 1000-volt rating symbol. Two layers of insulation do the work: a high-dielectric white inner coating under a flame-retardant orange outer coat. If the orange cracks or the white layer shows through, the tool is done and should be destroyed, not taped up. Klein is clear that insulation only reduces the chance of injury on contact, so de-energize whenever you can.

Yes, within limits. The shaft is hollow with a 6 inch (15.2 cm) shank, so the bolt or stud can pass up through the driver. That is what makes it workable on stacked circuit boards, long machine screws, and protruding studs in panel work. A nut sitting further than 6 inches down the rod is past what this one reaches.

Two SAE sizes: 5/16-Inch (646-5/16-INS) and 5/8-Inch (646-5/8-INS). Both are inch sizes, not metric, and the Tip-Ident marking on the handle lets you pick the right one out of a pouch without reading the shaft.

No. The 646-INS has a non-magnetic steel shaft, so it will not hold a loose nut in the socket for you on an overhead or blind start. If magnetic retention is what you need on a panel build, this hollow-shaft insulated driver is the wrong tool for that part of the job.

The two-color insulation is the inspection method. Orange outer, white high-dielectric inner: any white showing through means the tool gets pulled and destroyed. Crews inspect before each use, keep the tools clean and dry (moisture and surface films conduct), and wear eye protection. Each tool is individually tested to IEC 60900 and ASTM F1505, so your tool-control records can reference a recognized standard.

Pick hollow when the fastener sits on a stud, all-thread, or long bolt that has to pass up inside the shaft, which is common on stacked circuit boards and standoff hardware. The Klein 646-INS is the hollow type with a 6 inch shank. A solid-shaft insulated driver is the better choice for short bolts in tight pockets and for heavier torque, since there is no bore through the shaft.

It is a Cushion-Grip handle over high-dielectric plastic, shaped for more torque and comfort than a bare plastic handle. The grip and shaft measure 1 inch across in both height and width per the published dimensions, and the orange insulation runs down the shank to the working tip.

Yes, the 646-INS insulated hollow-shaft nut drivers are made in the USA, which matters on public and institutional jobs carrying domestic sourcing requirements.