The 12mm Slotted MDS Dropout is the chip system employed by some of our legacy trail bikes. You like chips, dont you? Who doesnt? The 12mm Slotted Dropout Chip uses a standard derailleur mount for maximum compatibility and is made of cast and machined 6061-T6 aluminum, with a fender eyelet. When you get an MDS-equipped frame youre getting the option to set it up however you want. You can run a 142mm x 12mm thru-axle rear end with a direct-mount Shimano hanger, standard 135mm QR or The Mighty Singlespeed. Our complete bikes that feature the MDS will ship with whatever chip is compatible with the derailleur spec. The MDS gives you not just different build options, it also lets you use a more varied selection of parts for your frame-up builds.