to use the part it attaches to the end of a 3/8' extension just like a socket. basically its a socket to allow you to turn your piston back into to rear caliper. its square and every side is a different application, nissan, subaru, ford etc.
a parts store may have it in stock under special parts, i just wanted to give you a good example. you should be able to get one. print it out and take it with you.
Don't set the parking brake. This should be obvious. The parking brake handle simply engages the rear brakes. If they are engaged, how are you going to compress them?
Compressing the piston - DO NOT use the C-clamp. The rear pistons must be compressed by turning them (I think it was clockwise) into the caliper. There is a special tool that I'm told is about $10. Or you can do it the way I did, use a good pair of needle nose pliars. You will see two notches in the piston where you can plant the pliars and use every ounce of strength to start turning the piston (it gets easier after the first few full turns).
You must transfer the side clips from the old pads to the new pads (unless they came with new clips, which mine didn't).
There is no stubborn torx bolt on the rears (thank goodness). Use a crescent wrench on the bolt that's there.
The manual I followed did not instruct me to put anti-squeal on the rear pads, so don't.
You will actually have to hold the rear calipers in place while you bolt them back down, due to the springs on top of the brake pads. This was the most difficult part (2nd to compressing the pistons, though). Make sure the pistons are fully seated to make this a little easier, and you'll probably need a buddy to hold the caliper down while you slip the bolt through.
http://www.hotrod.com/howto/51360/
