The Endura MT500 Rout Insulated Pant is built around Polartec(R) Alpha(R) insulation, a fabric that holds warmth on the descent and releases heat the moment a climb picks up the effort. A 2-layer water-repellent outer with a DWR finish sheds rain and trail spray without adding bulk, and zipped thigh vents give a rider manual control over temperature beyond what the fabric handles on its own. The Rout Fit stays loose through the leg, built for pedaling hard without fighting the pant. What Our Gearhead(R) Experts Are Saying:"I've climbed hard in these on freezing mornings without unzipping a single vent, and the Polartec Alpha still keeps me warm the second I stop moving at the top. Nothing about them traps heat the way old insulated pants used to."