Liquid charging is recommended when charging blends into refrigeration and air conditioning systems, and a liquid charger adapter is necessary for safe and fast liquid charging through the low pressure side of a system. Yellow Jacket® Liquid charging Adapter, Accessory Type: Accessory, For Use with: Quick Connect/Disconnect Refrigeration Hose, 1/4 in Male x Female, Aluminum, Blue, 1/4 in, Domestic