Clamp one end to your tripod, the other can hold a small reflector, hold back a twig, etc.
Once you have one you'll keep inventing new ways to use it.
The Plamp will attach to tripod legs whose diameter is between 0.9 and 1.4 inches (23 to 35mm). This includes Gitzo series 1,2,& 3 tripods and nearly all commonly used Bogen (Manfrotto) tripods. The Plamp will barely fit on Gitzo series 4 tripods but it is a tight fit.
The Plamp is 22” long, which is perfect for 100mm and smaller macro lenses. If you wish to use longer lenses with the Plamp, you may wish to extend its length with the PP-110 Plamp Extension.