Pearl Izumi P.R.O. Softshell WxB Mountain Bike Shoe Covers. Don't let extreme weather put a damper on your off road adventures. With the Pearl Izumi P.R.O. Softshell WxB Mountain Bike shoe covers covering your mountain bike shoes, your feet will be nigh impervious to precipitation and cold. These shoe covers feature .R.O. Barrier WxB 2 Layer stretch fabric that's completely waterproof as well as breathable. Add in the Primaloft insulation, and your feet will stay plenty warm as well in the nastiest weather. They're plenty tough, built to last, as well as easy to put on and remove.