The MagPul PTS Rail Vertical Grip / RVG is made specifically for 20mm MILSPEC rails. This vertical grip fits directly onto any rail segment and secures with two flat head screws. This grip is made from Magpul's special polymer so it's extremely lightweight and durable. The grip is textured and ribbed for grip with gloves or bare hands. At 3.5" tall it's not ideal for those with big hands but it does provide a stable vertical pillar to secure the front of your rifle.