Originally Posted by Dave in Kansas
The holder for the end of the film box so you know what film is loaded in the camera. Especially useful if you have more than one camera loaded with different films.
I use heavy duty packing tape to fix the box end to the back of the camera. I have done this to several bodies where there is a window in the film door, it's just easier to read.
Right now in Spain they're holding the Running of the Bulls,
followed by the Soiling of the Pants, and the Burying of the Idiots.