UMI's boxed lower control arms utilize our Roto-Joint technology for a bind free performance and quiet comfortable ride quality. The boxed control arms are fabricated from 0.120 wall thickness rectangular tubing, CNC machined drawn over mandrel bushing holders and MIG welded end caps to keep out unwanted road debris. Each control arm features the correct provisions for adding a stock or aftermarket rear sway bar, sway bar holes are reinforced with a 0.120 wall thickness steel sleeve that is TIG welded and sanded into place. The solid construction combined with the delrin lined Roto-Joints eliminate control arm flex and bushing deflection for improved traction and reduced wheel hop. The Roto-Joint design is a pivot ball lined with a greaseable delrin race designed to offer 28 degrees of total unrestricted movement, more than adequate for a bind free, low friction operation. The Roto-Joint design improves performance over the factory rubber and aftermarket polyurethane bushings by allowing the suspension to articulate correctly, and provide precision handling. The installed UMI Roto-Joint allows rear end free movement when high handling, auto cross or road race is a concern while still being a 100% streetable setup. The installed delrin race, which lines the spherical ball, absorbs shock and road noise for a quiet and smooth operation on any street or track driven vehicle. This control arm set features Roto-Joints on both sides of the control arms. This is designed for maximum performance and suspension travel. Roto-Joints are greaseable and low maintenance making an excellent street setup for your cruiser or race car!