AFSE Flashtubes fit all of the standard Flash Heads such as the Classic #001 and #002 Heads that had no modeling light feature. They also fit the new Extra Small Basic Heads HSBC.
The Flashtubes push/pull straight in/out and they will last for tens of thousands of flashes or one face down fall onto a hard surface.
Any of the Heads that have a modeling light would use the AFTE instead of this one.