The M194 Fragmentation/Percussion Grenade is the most commonly-used grenade during the Second Extrasolar War, originally used by the ISA. It is nicknamed "Door Knocker" for its tendency to catch enemy soldiers off-guard and is manufactured by ISA.
The M194 uses a slow fuse as a backup igniter, and it has indicator-lights that slowly light up when triggered, going from green to red as it comes close to exploding. It is able to kill a man within 2 meters of the explosion.
A common tactic for soldiers is to "cook" a grenade for a few seconds prior to release, so that it takes much less time to explode, or explodes almost immediately upon reaching its destination; this prevents the enemy from using up those precious few seconds prior to the grenade's detonation needed for them to successfully avoid the grenade.
This grenade is useful in both single player and multiplayer, and can be a priceless weapon when you need to take out many enemies without endangering yourself, especially when playing on Elite difficulty where the AI of the enemy is very high and you lose health much easier.
Note: Helghast will throw grenades at you if you take cover for too long.

The TR-X Teslite Grenade is a petrusite powered device that emits electricity by extracting it from the environment and then releasing it in one big blow. When armed, the guard plates around the coil open up and the top segment starts spinning. Upon reaching full charge, the grenade zaps anyone and anything in its proximity. It has about the same area of effect as the M194 Fragmentation Grenade but keeps emitting electricity for a couple of seconds and is also manufactured by ISA. It is infrastructure friendly, as it doesn't explode in a conventional sense instead sending a constant electrical blast into its target electrocuting surrounding individuals including a careless user.