For those times when you need to transport just one more bike, the MHS Duo Add-On 1-bike has you covered. Compatible with the MHS 1+1, 2+1, and 3+1 bases the MHS Duo Add-On saves you the hassle of buying a new rack to haul more bikes and bring more friends. The MHS Duo Add-On 1-bike features the same look and functionality as the MHS Duo Tray. Consisting of a singular, stylish bike tray with tool-free dual-wheel clamps with no frame contact, the MHS Duo Add-On is ready to attach and go right out of the box.