The RX4 + caliper is based on 25 years of experience in the design and manufacture of hydraulic disc brakes, transferring the knowledge and skills acquired to the world of braking from mtb to cyclocross and road.A precision CNC machined monoblock design results in a stiffer caliper for unmatched feel and modulation.The RX4 + calipers come in different models:a Postmount caliper, Flat Mount Front Direct and Flat Mount Rear Direct calipers with the addition of a new Flat Mount caliper.Calipers designed to fit 140, 160 and 180mm discs.Slim, lightweight 4-piston design.Monoblock design creates a stiffer caliper that reduces fuzzy lever feel and brake pad rubbing.Available in black, silver, red, blue, purple and orange.CNC machined from 2014 T6 aluminum.Mineral oil tweezers will have an M marked on the cap.Dot brake fluid calipers will have a D stamped on the cap.The RX4 + caliper is designed to work with the following Shimano and Campagnolo brake systems.(mineral oil, Shimano recommended for Shimano application, Campagnolo / Magura recommended for Campagnolo):Dura Ace Di2 R9170.Dura Ace R9120.Ultegra Di2 R8070.Ultegra R8020.105 R7020.Di2 R785.RS685.GRX RX810.GRX RX600.GRX RX400.GRX RX815 Di2.GRX RX817 Di2.RX4 + calipers compatible with Campagnolo:.Super Record.Record.Campagnolo H11.RX4 + calipers are designed to work with the following brake systems (with Dot Brake Fluid):Sram Red eTap AXS.Sram Red.Sram Force eTap AXS.Sram Force.Sram Rival.Sram apex.Sram S900.Shimano and SRAM brands are trademarks not related to Hope Technology.