Also here.

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And yes, I've already used it. LF seized up on track one day, cut my afternoon short. Was looking at reman'd cailpers for $50-100 which is still relatively cheap, but was shocked to find these. As long as the inside of the cylinder isn't scored or anything, there's really no going wrong with this. Simple disassemble, use this kit to replace every moving/rubber part of the caliper, then make sure you flush/bleed really well.