Klein Tools 66004 2-in-1 Impact Socket, 6-Point, 3/4 and 9/16-Inch

The 66004 holds two coaxial spring-loaded hex sockets, 3/4-inch and 9/16-inch, in one single-ended body. You change size by pushing the socket onto the fastener, no second hand and no swapping sockets on the gun. That is the point of the tool for anyone up a pole or on a ladder running both nut sizes on the same hardware.

Yes. The 66004 has a 1/2-inch square drive and is impact rated, so it goes straight onto a 1/2-inch drive impact wrench or impact driver adapter. Klein lists it as engineered for impact drivers including their own 1/2-inch Compact Impact Wrench (BAT20-CW and BAT20-CW1).

For impact work, yes. The 66004 is a 6-point design, so it bears on the flat sides of the hex rather than the corners, which is what keeps weathered or galvanized pole hardware from rounding off under high torque. A 12-point is faster to index on a hand ratchet in tight quarters but gives up that corner protection, so it is the wrong choice on an impact gun.

It is a deep socket, measuring 3.12 inches (7.9 cm) in overall height with a 1.1 inch outside diameter across both width and length. That depth is what lets it reach down a threaded bolt or stud on pole hardware instead of bottoming out on the thread, and the 1.1 inch body keeps it slim enough to get into a bracket.

The 66004 uses a cross hole design specifically to stop the adapter and socket separating unintentionally, which matters when you are working aloft and a dropped socket is a dropped-object incident. Pin and ring it through the cross hole on your drive and it stays put.

That is the trade it makes. Instead of carrying a 3/4-inch and a 9/16-inch deep impact socket and swapping on the gun, the 66004 carries both sizes in one 8 oz tool with a single 1/2-inch drive. If your work only ever hits one of those two sizes, a plain single-size deep impact socket does the same job; the 2-in-1 earns its place where pole and bracket hardware mixes both.