StopTech Cryo-Stop rotors for the 02-07 Subaru WRX & STI are a cryogenically treated, smooth faced, premium rotor casting. They use the same premium rotor castings as a StopTech Powerslot slotted rotor but do not have the slots machined into them to help reduce costs. This rotor option is meant to bridge the performance and price gap between basic replacement rotors and slotted performance rotors.
StopTech Cryo-Stop rotors are not designed or intended to outperform their slotted counterparts. Cryo-Stops will outperform and outlast OEM replacements because they are a cryogenically treated, premium rotor casting. Cryogenic treatment is a one-time process in which the rotor is quickly cooled to -300?ꒁF and then slowly brought back to ambient temperature. StopTech's cryogenic treatment process permanently changes metallurgy, resulting in a denser, stronger rotor able to withstand substantial braking forces for long periods of time; up to three times as long as an untreated equivalent rotor as well as being less prone to warping.
In addition to the cryogenic treatment Cryo-Stop rotors have an electrostatically applied finish designed to withstand 400 hours of saltwater exposure without rusting. This electrocoating (E-coating) finish, provides long lasting corrosion protection in the critical hat and cooling vane areas. So now your rotor will not only perform for a longer time, but they will look good longer too.