From Wolverine Airsoft we have the Invictus Quad Rail that comes in at 10" Length.
The Invictus Quad Rail features picatinny rails on all four sides. This rail is manufactured in-house at Wolverine's manufacturing facility in Kingsport, TN, USA and comes standard on the MTW Milspec Series.
Features
Tension-Mounting system (no more lock-block)
Integrated QD sling mounts
Picatinny rails on four sides
Backward-compatible with original MTW barrel nuts
Manufactured in-house by Invictus Manufacturing, USA
6105 T5 Aluminum
Milspec Black anodized