Klein Tools 631 Tool Set, Nut Driver Set

If you’ve ever dropped a nut into the abyss behind a fuse box and muttered something you wouldn’t say in front of your grandma, you’re not alone. Working with fasteners in tight spots is part of the trade. Having the right nut driver set can be the difference between finishing a job clean—or inventing a few new curse words.

That’s where the Klein Tools 631 Nut Driver Set comes in. It’s a 7-piece lineup with hollow shafts, classic Klein cushion grips, and the type of build quality you’d expect from a tool that proudly flashes “Made in USA” on its sleeve.

Let’s tear into this set and see if it’s all torque and no twist.

What’s in the Box (and What’s Not)

The Klein 631 kit includes seven nut drivers with hex sizes:

• 3/16″
• 1/4″
• 5/16″
• 11/32″
• 3/8″
• 7/16″
• 1/2″

Each has a 3-inch hollow shaft, except for the 3/16″ driver. That one? Not fully hollow. It bottoms out early. Could be a dealbreaker for some.

Out of the packaging, you immediately notice the build. No loose ends. No sharp molding seams. The shafts are chrome-plated steel, and the handles are that iconic orange-and-yellow combo Klein fans recognize from a mile away. It’s not fancy, but it screams “get stuff done.”

And no pouch? Nope. This set comes loose. You’ll want to plan a better storage solution if you hate rattling drawers.

First Impressions

Grabbing one of these for the first time feels like slipping into a pair of old work gloves—familiar and right. The cushion-grip handles are shaped for torque. No overthinking here. No gimmicky texture or glittery rubber inserts. Just good, grippy, oil-resistant handles that don’t feel like they’ll melt after three weeks in your truck.

The ends are color-coded and marked with size indicators, so if you organize them in a tool bag, you won’t be playing a guessing game every time.

The shafts are smooth but sturdy. The hollow design comes in handy when you’re working with long bolts or threaded rods. HVAC techs will know exactly what I’m talking about. Same for electricians who need to deal with old panel boxes that seem to have screws the length of chopsticks.

Performance Check

I ran these through a week of work on HVAC installs and general electrical jobs. Here’s what stood out:

• Torque transfer is excellent. You can crank these without slipping or hand fatigue.
• The hollow shafts handled 4″ bolts cleanly—except, again, for the 3/16″ one.
• The tips fit snug. No rounding. No wobble. They’re machined right.
• Dropped one off a 6-foot ladder. Bounced. No cracks. Just a scuff and a scowl from the guy below.

The internal flange on the shaft holds up. No twist-off issues. And because these aren’t magnetic, there’s no junk sticking to the tip every time you pull them out of your bag.

Would magnetic be handy sometimes? Sure. But not everyone wants that. For guys working around sensitive electronics or metal shavings, the non-magnetic version can actually be a blessing.

Stacking It Against the Competition

So how does it hold up to other sets?

Milwaukee’s nut drivers look flashier. But the handles are bulkier, and they’re usually imported.
Craftsman sets are cheaper. But they feel cheaper too—less torque, softer steel, shorter lifespan.
Wiha or Wera might tempt you if you’re the European tool type. But those prices? Oof.

The Klein 631 strikes a middle ground. It’s not over-engineered, but it’s definitely built with care. If you’re in the field daily, this set punches above its weight.

Maintenance and Warranty Talk

Keep them clean. Wipe ‘em down after use. Store them upright if you can. That chrome plating will hold up, but like any tool, don’t treat it like a hammer.

Klein backs their tools with a limited lifetime warranty—basically if it breaks under normal use, they’ll make it right. Just don’t go using it as a pry bar or punching holes in drywall and expect a freebie.

Final Thoughts

This Klein 631 Nut Driver Set might not come with glitter, lasers, or Bluetooth (thankfully), but it does come with something far more useful—reliability.

It’s the kind of set that’ll still be in your bag five years from now with the labels half-faded but the grip still solid.

You’ll probably lose one before it breaks.