Features: Boosts load capacity up to 2800lbs with the SSR 313 54 air helper spring kit, enhancing stability and ride comfort during hauling. Featuring progressive spring rate technology and compression capability, these spring ensure consistent performances. For truck owners and commercial operators needing upgraded suspension systems in for 1500/2500/3500 carrying heavy equipment or cargo. Optimizes vehicle control when transporting construction materials, campers accessories, or bulky loads across worksites, and uneven terrain. Engineered as direct replacements, these helper spring reduce body roll during turns while reinforcing rear suspension integrity. Specifications: Material: Rubber, Metal Size: about. 13.5x26mm/0.53x1.02in Pattern: 1pc/2pcs Part Number: SSR-313-54 Applicable Model: for Promaster 1500 2500 3500 Package Includes: Package 1: 1pc Rear Air Helper Spring Package 2: 2pcs Rear Air Helper Spring note: Please allow 1-2cm errors due to manual measurement. Due to difference between different monitors, the picture may not reflect the item actual color.