Comparison : Item # WP6305, 2 Stage Water Cooled Compressor (6000 Series)
Item # WP6310, 3 Stage Water Cooled Compressor (6000 Series)
Item # WP6442, 2 Stage Water Cooled Compressor (6000 Series)
Item # WP6550, 5 Stage Water Cooled Compressor (6000 Series)
Item # WP6550 BasSeal He-B, 5 Stage Water Cooled Compressor (6000 Series)