The vocas 15mm swing away bracket attaches directly to the rear of the mb 430 and mb 435 matte box and allows the user to mount the matte box onto 15mm rails when twisting the red knob of the swing away bracket the matte box moves forward and releases from its locked position allowing the user to swing the matte box away from the lens this swing away bracket can also be fitted with a 19mm rails adapter allowing the matte box to be used on the standard 19mm rails