Double Ball Mount for Subal Housings L&R pair Double ball mounts and "D" ring for Subal Housings. Our unique double ball adapter provides (2) 1 inch diameter ball mounts on each side of your Subal Housing as well as an integrated "D" ring. Now you have an uncluttered method to mount additional arms or focus lights. Sold in a set with left and right mounts. Sturdy stainless steel construction with bonded composit ball ends.