ITEM NAME:AC Quick Connector Adapter Coupler Auto A/C Manifold Gauge Low/High HVAC Description: - These Low/High side retrofits/adapters/fittings will convert your old 3/8"; or 7/16"; R12 - charging port and make it accept the R134a quick disconnect hose. - Fittings Have Removable Schrader Valves - High: 3/8'' - Low: 7/16'' Package Included: 1 Piece 19mm Blue Cap 1 Piece 22mm Red Cap 1 Piece Blue low side quick coupler 1 Piece Red high side quick coupler.1 Piece Blue low side quick coupler. 1 Piece Red high side quick coupler. Car & Truck Parts. - charging port and make it accept the R134a quick disconnect hose. - These Low/High side retrofits/adapters/fittings will convert your old 3/8"; or 7/16"; R12.