Main Frame: Commercial grade 50mm * 100mm * 2.5mm square tubing with electrostatic power-coating ensures ultra durability. Upholstery: High-density poly-foam offers comfort and endurability. Bearing: High-precision industrial grade ball bearing ensures smooth operation and rust protection. Adjustment: Elastic adjustment allows users to adjust upholstery easily and precisely. Handles: Anti-slide knurling aluminum handlebar.