Handstops are a low-profile foregrip accessory that provides stability for the support hand. It functions by acting as an index-stopping point for the offhand by preventing the hand from slipping too far off the barrel.
Be sure to check the height of the foregrip; a handstop should be at least small enough to fit the size of a finger. If the length is tall to fit the size of half a hand, it's likely a stubby vertical foregrip.
