Riding in the cold is hard enough, but add a pair of sopping wet shoes into the mix, and your bike ride just turned into an ambulance ride to the hospital. Well, toe-losing hypothermia might be a bit of a hyperbole, but the lesson remains the same -- you won't be having any fun with freezing feet. That's why Castelli created the wind and water-resistant Estremo Shoe Covers to combat the fun-thwarting attempts of winter.Made from a micro-injection rubber compound, the Estremo covers are durable, water-resistant, and wind-resistant. They use a thicker, weightier design than you normally see from Castelli, but this is to serve the purpose of all-weather coverage. In fact, the thermal density is so effective that Castelli recommends the Estremo covers for temperatures as low as 23 degrees Fahrenheit.And while that is impressive, we're equally enthused that Castelli introduced measures to combat the covers from losing their shape during repeated entry and exit. To do this, a waterproof 3M zipper runs from the ankle cuff to the bottom of the heel -- no more stretching and tearing just get your foot in the cover. Castelli also added reflective accents throughout the covers for a touch of added visibility in low-light conditions.The Castelli Estremo Shoe Covers are available in five sizes from Small to XX-Large and in the colors Black/black and Black/white.