This is a F.A.B. Mag Well known as the MOJO, model FX-MOJOB.
The MOJO transforms the standard AR Magwell into a comfortable and ergonomic foregrip with a flared and extended magazine well that enhances reload speed" while adding an ornamental aspect to the civilian firearm.
Features:
Replaceable grip area (Comes standard with the Tactical grip and one Mask grip)
Easy installation
Durable and lightweight