If you need to replace your Shimano road brake pads, the R55C series pads are the correct style. For more recent 10 and 11 speed Dura-Ace, Ultegra, and 105 series brake calipers, the R55C4 pad is the current replacement pad. Shimano also refers to cartridge pads as "shoes", which can be confusing, but goes back to the days of integrated pads and holders being called brake shoes. See the comprehensive list of compatible Shimano brake pad calipers/holders below if you aren't sure about which system you have.

The R55C4 Brake Shoe compound was developed in conjunction with the R1900 Dura-Ace group to deliver consistent stopping power, control, and modulation on aluminum rim surfaces in wet or dry conditions. Shimano's braking systems are the best in the business and the pads as the only point of contact, so they must get the job done, and they do. Durability and consistency are essential to rider confidence so the everyday performance of these brake pads is greatly appreciated by cyclists. The segmented pad surfaces allow heat, dust, and water to release during use, with plenty of pad surface for power and control. Shimano includes one pair of brake pads (for one caliper), with the two set screws for installation.