Mods in The Division 2 are important upgrades you can make to your weapons. These include things like scopes, sights, grips, and barrel attachments that increase certain weapons stats. Most of the mods aren’t available until later in the game, but you can unlock a few from SHD Tech perks early on.
To unlock these early mods, you’ll need to buy them from the Quartermaster at the White House using SHD Tech. Under the Perks tab, you can unlock four magazines, four barrels, two sights, and two grips. Each of these is limited to a certain type of weapon, like pistols or weapons that use 5.56 or 7.62 ammo types, but they give you a good baseline of upgrades for some of the earlier guns in the game.
Later in The Division 2, you’ll gain access to new mods as drop from enemies, as rewards for missions, and for completing Projects at settlements around the map. Some of these mods will require you to craft them. After you craft them, you can use them on any gun that they fit, and there’s no limit to the number of times you can use them.
While mods are mostly helpful and always a good idea to outfit your gun with, they aren’t universally beneficial. All mods have benefits and drawbacks. For instance, some might give you increased accuracy in exchange for stability, or increased headshot damage at the cost of reload speed. This doesn’t mean that you should avoid equipping your gun with mods. Just make sure you know what’s good and bad about each mod before you equip it.