NFA rules may apply. Read the ATF's final brace rule here.
The Flux Raider SBR Stock comes with 1 stock compatible gas cap. The brace gas caps are not compatible with the stock.
Installation video found here:
If you are having trouble installing your stock, we offer an install service:
LH Brace/SBR Stock Install and Tune (Brace/Stock not Included)
FLUSH, +1.5", +3"