The Pop Up Towing Companion Post Adapter for Curt Double Lock Gooseneck Hitch adapts to newer Companion 5th wheel hitches. It converts from Curt Double Lock gooseneck hitch to a square post connecting the Companion 5th Wheel Model 3500.Does not fit the older model 3000 Companion 5th Wheel hitch. For 3000 Companion use item 144753.ONLY fits Curt Double Lock Gooseneck Hitch. Does NOT fit the older model 3000 Companion 5th Wheel Hitch Only fits Curt Double Lock Gooseneck Hitch | Popup Towing Products LLC Pop Up Towing CDL-1 Curt Double Lock Gooseneck Hitch Adapter Post to RVK3500 Companion 5th Wheel Hitch