LD Systems STINGER SUB 15 G3 CB Dolly Board for Stinger® G3 Subwoofer 15" Models Made of polyurea coated 18 mm birch ply for extra strength and durability, this stackable dolly board is custom fit for the Stinger® G3 Subwoofer 15". It securely attaches to the sub with two integrated butterfly catches and features four heavy- duty castors with 100 mm wheels for easy movement. The sub can be left on the dolly for the gig aby simply locking two of the castors into place.