Shimano Ultegra BR-RS785 Hydraulic Disc Caliper, Post Mount, Finned Pads, Ceramic Pistons, Mineral Oil
6870 Series
https://bike.shimano.com/en-EU/product/component/ultegra-6870-di2/BR-RS785.html
Resin Compound
Comes with Front hose length, but can be used in either front or rear position with the BH90 Hose Kit