0-50 PSI: CGA INLET/ 1/4 NPT OUTLET,Works With HPLC,A 0-50psi single stage cylinder regulator for air. CGA inlet and 1/4" NPT outlet. Requires adapter 220-91287-00 for 1/4"NPT - 1/4" Swagelok output format to ELSD-LT gas tubing.,Not required if user wishes to use 'house' air/nitrogen.