Answer:
C47 may seem like a fancy word, but in the film world, it is the name of one of the simplest, most useful and versatile tools, which is commonly knows as a clothespin.
Following are major uses of C47 on a film set.
1) Lightning Purposes
C47 are used for attaching materials like gel and diffusion to the adjustable flaps, that control the direction of light
2) Adjusting Wardrobes
C47 are used to shorten, tighten or redesign a material of clothing for a specific purpose. It avoids permanent change and the hassle of sewing.
3) Modifications
These can be used for temporary repairs or to modify the set and shooting locations, e.g if a curtain is not hanging properly, C47 can be used