DOUBLE OVERDRIVE TRIKE TRAINER - With two identical progressive resistance drums - Aluminum drums: 3.25'' (82.5mm) diameter, 1/8'' (3mm) wall thickness - End caps: Molded polycarbonate - Drums are lathed on the axle for precision runout and balance - All drums are dynamically spin balanced, and will not distort in heat or sunlight - Bearings are greased and sealed, and do not require maintenance - Steel framework is zinc-plated and powder coated for ultimate durability - Product dimensions: 21'' x 4.25'' x 10'' (53.3cm x 10.8cm x 25.4cm) - Change the resistance level simply by changing gears - Powered by our patented ARC Technology, the OverDrive Trike Trainer delivers real-road resistance - Lightweight, compact and easy to transport and store - Accommodates 16'' to 700c wheels and requires no clamping on the rear skewer - Identified by one red cap on the rear drum (the Mag Trike Trainer has two red caps on the rear drum) - 100% designed and manufactured in USA - Lifetime warranty