The Gaslow 27mm Clip-on Adaptor 01-1673 is used to Convert 27 mm clip on Gas cylinders, such as used on Calor Gas patio gas cylinders, Calor Gas BBQ Gas cylinders and BP Light gas cylinders to 21.8LH screw thread. Output pressure through the adapter will be cylinder pressure. Normally connected to a bulkhead mounted 30mbar regulator via high pressure pigtails.