This is a replacement lid for the stock headlight lid on the driver's side. The intent is to let cool air in at the spot where cold air induction devices such as the Crazy Red Miata and Racing Beat intakes suck air in (the intakes with a "U" bend puting the mouth of the K&N type filter behind the driver's side headlight. Not intended to be used with Jackson Racing type intakes. It is made of metal and comes primed in black. I suspect it is a stock miata headlight lid run through some sort of machining process to cut four raised louvers in it. It is a perfect fit and needs only a quick trip to the paint shop to match the color of your miata. The cost of the lid shipped to me from Rod Millen Motorsport was about $65. A quick $35 to have it painted.
Even I could install this. Raise the headlight cover with the dash switch. Remove the four phillips screws holding the black headlight shroud in place. Remove the shroud. Loosen the four bolts holding the original lid on (a nut driver works fine here). No need to remove the bolts because the old and new lids have four forks for attaching the lids. Remove the original lid. Slide the new one on. Lightly tighten the bolts. Check alignment of lid with engine hatch by lowering the lid. Raise lid. Adjust as necessary. Tighten bolts. Replace shroud and four phillips screws. It took longer to write this than to do it.
Very cool looking. Now no need to raise headlights during the day to increase air intake. Not possible to ascertain whether it really adds to performance but in theory it should. Many original equipment autos have louvered intakes. I recommend it.