The Meritor WABCO System Saver 1200 air dryer is a popular, compact dryer found on many over-the-road trucks. It features a spin-on desiccant cartridge.
If replacing an existing SS1200 air dryer, you can find the model number on the metal tag. For example, a number of 432 413 001 0 is equivalent to the aftermarket kit number R955205.