Air operated with air purge. Universal couplers fits most hoses, evaps and condensers. 2-1/2 gallon capacity for busses. Forward and reverse flush without changing hoses. Clear filter bowl with cleanable screen for visual inspection The AFM100 A/C Flusher machine is a valuable tool to any technician. Avoid repeat repairs due to system contamination. The purpose of flushing is to remove debris and contaminated oil, which renews and extends the life of the A/C system. This is done with only shop air and a good flushing solution. Comes with 8 foot hoses and universal couplers that will feet most connections, the 2-1/2 gallon capacity can do cars to busses. Most cars will only require 2 quarts where as a bus may need a full 2-1/2 gallons to reach all the hoses. There is a clear filter bowl for viewing of flushing solution to see what you are removing.