The Aston Seals GRB type guide rings have been developed to substitute traditional bronze guides in hydraulic cylinders. They guide the rod or the piston and prevent metallic contact with the cylinder when radial forces act perpendicular to the direction of movement. Since GRB guide rings are machined, the thickness can be very accurate for high precision guiding. The compound used for these guides assures an exceptional low friction and high speed performance, a high compatibility with nearly all media due to the chemical resistance which exceeds that of all other thermoplastics and elastomers.