ALEKO U-Groove Wheels for Round Track Power Wheel Gate Wheel for Sliding Gates 3 1/2 inches for U-Shape Tracks ALEKO high quality engineered galvanized 3 1/2 inches (90mm) wheel Designed for high traffic commercial sliding gate track applications Designed for loads up to 500Lb (250kg) Never needs greasing or maintenance Designed for round profile tracks. Diameter: 3 1/2 inches