An improvement on an old idea! Works well; if you need to block out that annoying gray or blue rectangle from your LCD or DLP projector really quickly, this is the unit for you! Easy alignment (just set on top of the projector as shown and cut the plastic blade and/or swing-arm to the needed length)! If you know what this is, then you'll see how it is remarkably useful as a blanker for non-dimmable sources (such as zenon-arc projectors), with its approximately 1/2 second open/close quickly to/from opaque. Make your own simple remote! Easy to fit to DMX or other control systems as simply as a relay closure or toggle switch.