This is a gobo. It's just one of the many that come with the spotlight menu zoom from aperture. A gobo is an acronym derived from Go's before optics, which hints to where it goes in correlation with a fixture. As you can see, moving the gobo closer or further to the light source or subject changes how sharp or soft the pattern becomes. Because Gobo's come in all shapes and patterns, these little pieces of metal are some of the best ways to add shape, dimension and interest to your scenes. You also aren't only limited to the ones that are pre-made. You can go custom order your own gobo's. So what are you waiting for? Go make it interesting.