Gooseneck hitches are not my thing. But I know there are various designs that use the pop-up/roll-over/turn-over/removeable ball concept. As Rich1961 said, The B&W Companion 5er hitch was designed to be compatible with a B&W Turn-Over Ball hitch. The POP/flip-over ball is a different design than the TurnOver Ball, so I doubt that the Companion 5er hitch will plug into it. However, either B&W or POP may make an adapter kit that makes the Companion Hitch work in the POP hitch.
Grumpy ole man with over 50 years towing experience. Now my heaviest trailer is a 7,000-pound enclosed cargo trailer, RV is a 5,600 pound Skyline Nomad Joey 196S, and my tow vehicle is a 2012 F-150 EcoBoost SuperCrew.