This silver replacement crossfader is for the Q-3433MKII, Q-2422MKII, Q-2221/SX, Q-2422/SX, Q-3433-SX, XDM-250T, Q-221 and the Q-D3 mixers. SPECIAL NOTE: The older model Q-2221 that is dark grey uses ONLY the FF-4 crossfader. The Q-2221/S mixer uses ONLY the FF-4/S