STF-12 Compact is an Italian 12 gauge pump-action shotgun manufactured by the FABARM (Fabbrica Bresciana Armi). It is intended mostly for professional use by various law enforcement and military operators. These shotguns also can be used for practical sport shooting, home defense and hunting, although some “short” versions might be not considered legal for civilian use in various countries.
It is very similar in performance to the Reinfeld shotgun with Average Shotgun Rebalnce installed: it has higher damage than default Reinfeld, but lower ammo count. Nothing else to say.
In order to make it work, you shoould extract archive content into mod_overrides folder
Notes, issues:
Default iron sights have a horrible quality. They use third person model instead of first person like the rest of the weapon because FP model misses some faces. They are perfectly usable still.