Abstract: A stabilizer device attachable to a king pin of a fifth wheel recreational vehicle requiring stabilizing for stabilizing the vehicle upon a support surface. A cup device, which is adjustably attachable to a substantially horizontally oriented support device, is positioned to accept a king pin member of the vehicle. The cup includes a locking device attachable thereto for securing the king pin by means of a lock. A screw member is secured to the bottom of the cup and passes through the support device. The screw member is vertically adjustable upon a threaded block member positioned upon the support device. A pair of handles extend sideways from the block member for easy adjustment. A pair of leg members are pivotally attached to the support device and are attached to each other by an adjustable brace device which provides rigid connection of the legs at chosen positions to secure the chosen angle of attachment of the legs to each other.