Taken from 365rider.com... "The Saucony Peregrine 11 shoes have been built on a reliable foundation of PWRTRAC rubber studs, sticky rubber that provides a confident grip on a wide variety of terrains in addition to PWRRUN cushioning, which ensures a responsive and protective feel, responsive uphill. and grip downhill with confidence. With even more protection than before, they have everything you need to move fast over any type of rough terrain. Characteristics: - For those runners who are physically preparing, these shoes are qualified for training and competition - PWRRUN midsole for greater energy return - Use: oriented to trail running - Neutral pronation - Stud length: 5 mm - Heel: 27mm - Forefoot: 23mm - Drop: 4 mm - Weight: 310 g Technologies: - PWRRUN The latest update based on traditional EVA that offers cushioning that provides even more energy return and durability than previous formulations. - PWTRAC Compound of the sole with great resistance to abrasion and maximum grip and traction, it has a coefficient of friction (COF) that is three times that of a traditional compound.' Item S20641-25 *new and never worn without box or tags