Fitment
Will this fit?
Fitment data still being indexed for this product. Ask BuildBot for a fit-check against your vehicle.
The compound
Project Mu H21.
Project Mu’s endurance answer, and the compound with the strongest reputation in oval racing — particularly short circuits. It gives up some outright friction to H20 in exchange for excellent fade resistance, strong modulation, long pad life and unusually low rotor wear. Used in GT, V8 Supercars, NASCAR and Trans Am, front or rear.
Operating range200–850°C
Pad lifelong
Rotor weargentle
Cross-brand equivalents
Run something similar.
These are the compounds we stock for the AP Racing 4-pot RD42 (CP3215 D40/D42) whose published friction and operating temperature come closest to Project Mu H21. They are a starting point for switching brands — not a guarantee of identical feel, because each manufacturer measures friction on their own equipment.
Circo M119
Partial match50–800°Cµ 0.48–0.51
Circo’s sprint answer: around 0.5 friction from 50°C, so it works before the pads are hot. Rally and circuit.
Matched on published operating temperature only — one of the two brands doesn’t publish a friction figure, so this is a weaker comparison.
From $508Compare every compound for the AP Racing 4-pot RD42 (CP3215 D40/D42)
Fits the same caliper
More pads for the AP Racing 4-pot RD42 (CP3215 D40/D42).
Pairs well with
