Hallmark offers two different models of semi-hermetic compressor, HA air cooled and HG suction gas cooled which can be supplied as a compressor unit and air cooled condensing unit. HG (Semi-hermetic Gas Cooled) The semi-hermetic gas cooled range is renowned for its quiet running, ease of maintenance, efficiency and reliability. Suitable for conventional or chlorine-free HFC refrigerants, the HG range offers state-of-the-art suction gas-cooled compressor technology. HG models available: -HG single-stage -HGZ two stage -HG8/4 polar -DHG duplex compressor -SHG compressor units with receiver -SHG condenser sets, air cooled HA (Semi-hermetic air cooled) The semi-hermetic air cooled range is ideal for deep freeze applications using R22 and R404a. HA models available: -HA single-stage -DHA duplex compressor -SHA compressor units with receiver -SHA condenser sets, air cooled