The Meritor WABCO System Saver 1200 Plus air dryer is the latest upgrade to the original System Saver 1200. This model integrates the air system governor into the air dryer and has it's own purge volume. The 1200 Plus uses the same spin-on desiccant cartridge and purge valve maintenance kit as the original System Saver 1200 dryers.
If replacing an existing SS1200 Plus air dryer, you can find the part number on the metal tag. For example, a number of 432 470 001 0 is equivalent to the aftermarket part number S4324700010.