The dual inlet ports support the plumbing required for Hydro-Boost brake systems. The factory style plastic pump-mounted power steering reservoir does not have the extra inlet port that is required for Hydro-Boost. These remote reservoirs when used with Earls power steering pump adapters (PS0001ERL, PS0002ERL, PS003ERL, PS0004ERL) eliminate the plastic reservoir & allow easy plumbing for the outlet from the Hydro-Boost to the reservoir. If you don't have a Hydro-boost brake system, install the included AN plug on the extra inlet port.