Cooler brakes stop more reliably, and Shimano's BR-RS805/RS505 Flat Mount L04C Metallic Ice-Tech Disc Brake Pads use both cooling Ice Technology and a metal construction to provide the highest all-around stopping power in Shimano's line. On their own, the metal pads display reliable, high stopping power in wet or dry conditions, demonstrating consistently better durability over repetitive use than their resin counterparts. The pads' Ice Tech distinction refers to an additional radiation fin pad, made with an aluminum and stainless steel fin that improves the pads' ability to stay cool under hard braking. If you're running Ultegra BR-RS805 or 105-level RS505 hydraulic disc brakes on your bike and want a pad that will stop you in muddy, sandy, wet conditions, the L04C's would be tough to beat.