This is the Knights Armament vertical grip used on the M16A4, M4 Block 1 and also on the Mk18 Mod 0.
The vertical grip has been made by KAC, P&S Products and also by PAT, for use on the M4 RAS and M5 RAS rails with rifles with front sight base. For Knight's VFG, the first generation were marked as "Vero Beach" from roughly 1998 to 2003, and then marked without a City, only the Knights name and logo from 2004 for roughly the next 7 to 10 years. The current generation includes the Knights CAGE code as well as the KAC logo.
NOTE: This is a USED product, in good working shape, grades C to A-, will show some scuffs and possibly dirty.
This is current production, mil-spec marked Knights Armament and also CAGE Code. Most also are marked, Titusville, FL
Knights Part Number: KM-97098
Charlie's also sells Mil-Spec VFG manufactured by both P&S Products and KAC