This is a Lowel 40° Honeycomb Grid for use on the Fluo-Tec 250.
A 20° grid offers the most control over the spread of any light fixture. Use it to add drama to lighting effects. A 30° grid offers a little less control, but still provides a tight beam spread. A 40° offers the least amount of control. Use a 40° when the subject is to be isolated from the background that is ~4 - 5' away.