The kit will not be compatible with most aftermarket uppers that have integrated picatinny rails (e.g. FUKU 2, Mamba) -- This is due to there being an M4 magwell in the way!
We will be releasing our own carbon fibre uppers, which seamlessly integrate with the Paradox lower for a great aesthetic.
Aftermarket front barrels, and aftermarket CNC uppers that mimic the stock Action Army 'two part' upper, are compatible with this kit, and are a great way to add aesthetic flair!