Monroe 901721 Max-Lift Gas Charged Lift Support Nitro-Carburized Rod: For exceptional corrosion resistance and durability. Durable Plastic Rod Guide: Durable Plastic Rod Guide reduces potential rod abrasion. Main Seal: Main seal provides positive closure for high-pressure gas. Stop Collar: Stop Collar and Limiting Groove assure precise extended length. High-Strength Piston Assembly: High-Strength Piston Assembly with leak-resistant seal helps prevent fluid leakage around the piston, allowing the fluid to pass efficiently through the piston valving components, providing controlled lift and consistent performance.