As stated above these are absolutely brand new and unused, complete bolt carrier groups, just lube them up, install them in your upper, and start shooting.
I have two Lewis Machine and Tool (LMT) BCG's left to sell. The LMT's enhanced carriers use new BCM bolts, cam pins, firing pins and retainer pins. The LMT enhanced BCG are priced at $175 each delivered. No further price reductions on these items and no trades are needed at this time. Payment would be by a USPS or bank money order or by paypal (you pay any fees). Here are some links with more information on the parts.