The RF-90AT is near identical to the RS-45T but is slightly smaller for older model mixers that have a smaller chassis. This is the replacement crossfader for the DM1090, DM1190, DM1200, DM1235, DM1285, DM1600X, DM1635, DM1685, DM1720X, DM1800X, DM1920X and DM900 mixers.