Daniel Defense Vertical Foregrip, Fits Picatinny Rail, Mil-Spec Brown 21-067-05028-011 Daniel Defense's Vertical Foregrip Mil-Spec Plus Picatinny now includes soft touch rubber overmolding for enhanced grip wet or dry. Inside the grip is a Dual O-Ring water tight storage compartment capable of storing small parts. This vertical grip is extremely lightweight and utilizes a simple yet durable mounting method for 1913 Picatinny rail systems. Not Compatible with KeyMod or M-LOK rail systems.