Matte box is used on the end of a lens to block the sun or other light source in order to prevent glare and lens flare. It performs essentially the same function as a lens hood and also mounts in front of the lens, but usually includes adjustable fins called French flags. Another purpose of a matte box is to hold glass or plastic filters in place in front of the lens. Feature: ? Swing-Away : You can easily swing-away the mattebox without disturbing the camera from the tripod and rail system and mount the mattebox again on the camera within a second. The knob on the top of the swing-away bracket helps you to swing the mattebox from the setup. ? 2 trays design ? French Flag/Side Flags :reduing extra flares and removable. They are attached by hinge mechanism. ? Compatible with wide angle lenses. ? Compatible with 15mm rod ,center-to-center rails distance 60mm. ? Two 15mm holes on bracket by side,which makes you able to mount some other device by side.2pcs 15mm rod (20cm in length)included. ? 4pcs donuts ? Material:Made of metal and plastic Suitable for: wide angle lenses on DV / HDV /Broadcast /16mm/35mm cameras. Package including: FOTGA DP3000 M4 Matte Box x 1 Top Flag x 1 Side Flags x 2 Donuts (103mm,76mm,64mm,51mm) x 4 4"x4" Filter Holder x 2 15mm Rod x 2 top handle x 1