G&G Armament produces a specific G&G Armament Keymod Foregrip (also called a forward grip or vertical grip) that is designed for direct attachment to KeyMod rail systems, including their own G&G KeyMod handguards. 
 
Product Details
Design: The G&G Armament Keymod Foregrip is a short, compact vertical grip designed to improve weapon handling, stability, and control.
Material: It is made from a durable, tough polymer material that is also lightweight, often described as having the weight of plastic with the strength of metal.
Installation: The grip is easy to install by loosening an Allen bolt on the underside, sliding the anchors into the larger KeyMod holes, moving it forward to lock in place, and then tightening the bolt. An Allen key is usually included for installation.
Ergonomics: It features a textured or stippled front surface and ridged rear for a secure and comfortable grip, even when wearing gloves.
Compatibility: This grip is designed for use with KeyMod rail systems and is compatible with various G&G airsoft rifles that use this system, such as those in the Warthog or Predator series.