This is a small bracket intended for attaching LED lights to a Quadcopter frame that uses square aluminum booms. It will hold two 5mm LEDs, one at 90 from the boom and one at 180 degrees. It can be attached with a single screw/bolt or a zip tie (the notches are to keep it from slipping out from under the zip tie). Set of 4.
A note regarding ordering in the "polished" materials. The Polishing process enlarges the holes a very small amount. While most 5mm LEDs will still friction fit into them, a dab of hot melt glue may be required to keep them from vibrating loose.