This is the Litepanels 45 Degree Honeycomb Grid for 1X1 LED Lights.

Litepanels' Honeycomb Grids, compatible with all models of 1X1 fixtures, offer a convenient means of control of the LED light beam. Constructed of extruded ABS plastic with powder-coated aluminum honeycomb material, they're available in 90, 60, 45 and 30 degree versions, with 30 degrees offering the tightest control of the beam. In practice the grids, which slide into the 1x1's accessory rail system, function much like barndoors to control spill light, while their 3/4" depth is consistent with the slim-profile design which is the hallmark of Litepanels products.