Bushing kit. Left.W/380MM BRAKES. Rear. Right.W/380MM BRAKES. A Bushing, typically made of rubber, used to provide a surface for the Disc Brake Caliper guide pin to move freely. A Kit containing Disc Brake Caliper guide pin boots. Disc Brake Caliper Bushing. Disc Brake Caliper Pin Seal.. Guide Pin Seal. mount. Slide Pin Boot. Included with: Caliper.