Falcon Eyes has a wide assortment softboxes, which can be mounted on various brands of flash units using a speed ring (also known as adapter ring). This way you can save a considerable amount on the original softboxes of other brands. The outer diameter is 15.4 cm. With this adapter ring you can mount the inexpensive Falcon Eyes softboxes, snoots and reflectors on your Bowens, Linkstar, StudioKing, Jinbei, Qihe, Lastolite and Aurora flash units.