F1 Grenade

The F1 Grenade is a better suited for combat throwable, with the only similar to it being the more primitive Beancan Grenade, more suited for raiding than the F1 Grenade. The F1 Grenade has a fixed fuse of about 3 seconds unlike the Beancan Grenade which has a random fuse, which can either dud, explode in an instant or explode after a millennium. The F1 Grenade has received a huge buff in the September update of 2019.
It's rarely seen in combat, where it's meant to shine, but due to the buff, it is way more effective in that regard. Using it as an offensive grenade is way better than the Beancan Grenade, due to the fact:

• • it has a fixed fuse of 3 seconds, that obviously cannot dud
• • does not hiss like the Beancan Grenade
• • no one would expect you to use it
• • it now does improved damage and is now one of the few ways to deal with a turret in a base

But the downsides are as follows:

1. • depending on the way you use it, any player who pays attention to his surroundings can get away from it or take cover
2. • gives off a sound upon landing on a surface, which will alert anyone near it.

It's a weapon that has a very situational usage. You can keep enemies at bay with it, force them to go away or provoke them to rush you. If you want to use in more efficiently in combat, one possible way to counteract the fuse is by

1. • throwing it in a specific arc so that when it lands, there's a second or less of the fuse remaining.

Other important tips:

• • Explosive protection is a thing, but there is no exact way to counteract explosions fully with any set of armour, so this grenade will deal a devastating amount of damage if it hits, anyone healing behind cover is likely to get killed if they've been critically injured.

So cheap to make, one or two of these are great for small raids, throw em right through the crack in their 1x2's airlock and they have a hard choice to make.

As of the at-the-time-of-posting upcoming September update, they do more damage, and have an increased damage multiplier against Auto Turrets, taking around 10 to break one
EDIT: After testing, I have confirmed that not even Heavy Armor can save you from death from an F1 Grenade

Make sure to first exercise the throwing (and sticking onto doors & walls) of F1 grenades, because it's common for players that aren't familiar with the controls to either accidentally misthrow (drop it on the ground next to their feet and their team mates.. "RUN RUN RUN!!" - without forward thrust) or throw it instead of properly attaching it onto a surface.
Protip: attach an F1 grenade to the hatch of an armored door, when the people behind it are constantly peeking through it. The next thing they will see when they open it.. will surprise them, boom.

Damage buff makes this a very valuable weapon in pvp. Even against full metal players, which most players are usually geared down by comparison. The real question is it worth researching? It's half the GP of a beancan, but it's only 8 scrap per F1 at Bandit Camp. A single run up a road could net you a stack of F1 grenades at bandit with zero GP cost. Something to consider before you research these, if you feel compelled to do so.

You can purchase them for scrap and recycle them for gunpowder at Bandit Camp. Though it can be time consuming, it's better than farming sulfur, smelting charcoal and crafting it. Each stack of 5 recycles for 75 gunpowder.