G&G have shared details of their Tri-rail mount:
TRI-RAIL Mount
Add triple rails to your AR / M4 / M16’s barrel for additional attachments, or use them as a monolithic extension to your existing picatinny rails. The Tri-rail mount is compact, lightweight, and sturdy. If you are looking to mount lights or lasers on your rifle without a heavy/expensive RIS system, this is the perfect solution!Find your local G&G Dealer
G&G