The theory behind this ratchet is great. The wrench does work great opening the caliper. The problem I found was trying to attach the larger metal pieces to the wrench. These larger pieces open the bigger caliper where wider metal plates fit onto the wrench smaller plates, and open two pistons instead of one piston. One piston only needs the wrench with smaller plates on the wrench. This smaller plate part is actually part of the wrench and works fine. The larger plates fall off the smaller plates as you place the wrench inside the caliper. It needs smaller earth magnets to hold the plates together. If you don't need the larger plates in place for two piston calipers, you'll like the wrench. Or get a couple of small earth magnets and enjoy opening larger calipers as well.