Most manufacturers put a number related to Btu's of the unit in the model. If Rheem is no different then that 42 represents a 3.5 ton unit as there are 12,000 btu's / ton and 3.5 X 12 = 42.
3ton
4 ton
The tonnage of the RALB-042jaz system is 3.5 tons. Rheem heating ans cooling products include both indoor heating furnace units and outdoor air conditioners.
Two ton. the 024 designates 24,000 btu. 12,000 btu = 1 ton. 24,000 btu= 2ton.
Based on typical naming conventions - 24 - in the model number indicates 24,000 btuh nominal or 2 tons cooling.
Your first set of numbers gives you the tonnage, so this is a 2 ton; your "4" number represents a 460-volt electrical requirement
2
2.5
five ton
5 ton
3 ton
That is a 4ton