Dimensions:
Wide 1 m (3.2 feet),
Height 1.1 m (3.6 feet),
Deep 0.8 m (2.6 feet).
If you have a medium size system connected to a bottle packing in a cold area or very far from the system, B1 is the booster you need.
If you have a large system connected to a CO2 cryogenic tank, B2 is the booster you need.
We would call you