Hollow Plunger Cylinders  Double-acting Hollow Plunger Cylinders  Relief valves prevent damage in case of over-pressurisation  Baked surface can resist increased corrosion  Double-acting enables fast retraction  Nickel-plated,Website:http://www.dudemachinery.com, floating centre tube increases product life  Hollow plunger allows for both pull and push force  All models with CR-400 quick coupling and dust cap  Plunger wiper reduces contamination, extending cylinder life  Outer ring screw for easy installation  (excluding RRH-1001 and RRH-1508)