The Frag Grenade is a powerful grenade that can be found in Classic Mode, Arena, Arcade mode, Evoground and even Metro Royale.
Probably the most used Throwable in the game, the Frag Grenade deals damage once the countdown is over - this could be at your enemy's feet, in the air, or in your very hands, which would knock you.
A well-aimed Frag Grenade can instantly knock an enemy, or at least injure you greatly. This is the reason why many strategic players use Frag Grenades to soften up their enemies, and overpower them when pushing.