Respironics introduces performance tubing for use solely with the System One line of CPAP, APAP, and BiPAP Machines. This 15mm tubing is slimmer than standard tubing, lighter than normal tubing, while still maintaining superior strength and ability. To be used ONLY with the System One series of machines. This tubing is 15mm in diameter, but fits a standard 22mm mask and machine. This tubing is NOT compatible with the DS150 and DS250 models of the System One series.