What kind of regulator works with an IDI Ballistic BCD?

The BCD (buoyancy compensator/control Devise) low pressure line is connected to the second stage of the regulator. International Divers Incorporated devises are compatible with other manufacturers of two stage diving equipment.

Addition

Any regulator will work. It is not the regulator, but the size of the low pressure inflator hose. The low pressure inflator hose can simply be changed if there is a size (fitting) issue. This should not be an issue unless you bought a used regulator where the previous owner used a different inflator on their BCD such as an inflator you can breath from (which often has a larger diameter inflator connection).