Calumet MF6726 Speedbox Flash Adapter Mounts Directly to Any Calumet Speedbox and Can Be Used with Most Popular Portable Shoe-Mount Flash Units This flash adapter will accept most popular portable shoe-mount flash units and mounts directly to any Calumet SpeedBox. Simply slide your speedlight into the cold-shoe mount and attach it the outside rear of your SpeedBox. The adapter can be mounted to any light stand with a 5/8 stud.