This is the Shimano Dura-Ace BR-9000 R55C4 Cartidge Brake Shoe and Fixing Bolt Set. This set includes shoes for one brake, with two included fixing bolts.
Shimano R55C4 Road Brake Pads - Black - Cambria Bike
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SHIMANO Dura-Ace, Ultegra, 105 R55C4 Brake Cartridges : : Sports, Fitness & Outdoors
Brakes/Levers/Pads - Planet Bike East Brunswick Matawan / Old Bridge
Brakes/Levers/Pads - Pearland Bicycles Pearland, TX
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Shimano - Brakes, Levers & Pads - BIKE513