Nothing fancy, just plain works. Always use these for builds, never had a problem.

Got this to help bolster my parts bin for the AR. Its been a while since I had a new bolt let alone new gas rings. When I tried to move the bolt on this thing it was very stiff. I took it apart, dumped it in a bin with mineral spirits (get a walmart/lowes/etc) which is just a base level solvent totally safe for cleaning firearms and metal in general and way cheaper than hoppes9. Anyway after I soaked it for 20 minutes got all the grease and gunk off the parts, put some LSA gun oil on there and put it back together. For a week anytime I was reading, siting around I kept moving the bolt, oiling, moving it, oiling.. etc. It's perfectly fine and feels good. It's the full auto BCG doesn't have the back end of the carrier cut back or made into a half moon or any of the sillyness Colt did for a while to appease the gun control group. Make sure you check your AR to ensure it takes the full auto carrier. If you don't know what I am talking about do a little research and you will find out, its not that complex honestly. Its a good part, a bit expensive but it is a quality product. BEFORE you buy this, get a second AR of the same type so you have ALL parts duplicated for backup. After your second AR, if your AR can accept full auto carrier, then buy this with confidence.