Klein Tools 70552 Pro Folding Hex Key Set, SAE and Metric

Both are covered in the 70552. It's a 21 piece set: SAE in 3/32, 7/64, 1/8, 9/64, 5/32, 3/16, 7/32, 1/4, 5/16, 3/8 and 1/2 inch, plus metric in 1.5, 2, 2.5, 3, 4, 5, 6, 8, 10 and 12 mm. The keys are split across a 2 pack of folding holders, so one holder carries the inch sizes and the other the metric, and you grab whichever the job calls for instead of buying two brands of set.

Key blades run about 3.5 to 4.5 inches long, with a listed key length of 4.5 inches (11.4 cm), so they are extended reach rather than stubby pocket keys. That gets you into recessed set screws on luminaire canopies, shaft collars and similar hardware where a standard folding set bottoms out on the housing before the key seats.

No. The 70552 is not insulated, and the reinforced nylon handle is not rated protection against electrical shock. De-energize the circuit before using it, or use a tool that carries an insulated rating. Klein also warns against slipping a pipe over the handle for extra leverage, and against working without approved eye protection.

Flat, square-cut ends, not ball end. Square-cut means the key seats to full depth with maximum contact inside the socket, which is what keeps it from camming out and rounding the fastener under torque. The tradeoff is you cannot work at an angle the way a ball end lets you, so for an off-axis set screw you want a ball-end key instead.

Tension is adjustable. A #2 Phillips fastener at the pivot lets you tighten or loosen the keys so they stay where you set them instead of swinging free. Each blade also opens independently up to 270 degrees, so you can position one key at an angle for leverage without dragging the rest of the stack with it.

It's built to carry. Each folding holder measures 6.6 inches overall length, 2.15 inches high and 1.36 inches wide, with a 6.63 inch handle, and the full 2 pack weighs 2.01 lbs. That drops into a pouch pocket or a van drawer without a case.

Blades are heat-treated alloy steel, listed as CR-V, with a black phosphate finish. Klein calls the heat-treated steel out as rust resistant. Phosphate is a conversion coating, not a plating, so it holds oil well; a wipe of light oil before the tool goes back in a damp gang box is still worth doing.

Yes. The sides of each holder are open, so the outer keys can be pulled straight out without fighting the case. Combined with the 270 degree independent swing, you can pick one size and use it while the rest stay stowed.

Order Klein Tools 70552. It's the orange-handled Pro Folding Hex Key Set, 21 keys in SAE and metric across a 2 pack of folders. Same number covers the whole set, so a crew standardizing on one kit only needs the one line item.