DUO Traction Wheels are compatible with the REV DUO System and fit on a 5mm hex shaft. The hex shaft interface completely eliminates the need for expensive hubs or using potentially unreliable set screws. DUO Traction Wheels 60mm in diameter and larger have a hole pattern on an 8mm pitch enabling easy mounting directly to DUO Extrusion, DUO Brackets, and other 8mm pitch systems. All DUO motion products have a uniform 15mm width to make quick design swaps fast and easy.