Tranquilizers Rounds is another special type of ammo for pistols and it is the default ammo for the Tranquilizer Pistol. It is takes sedative damage over time against enemy but poor against armored targets.
These rounds are hollowed out to contain a dose of debilitating sedatives and virtually useless against armored targets. While not as practical as jabbing someone with a syringe, these rounds can incapacitate any target you wish to leave alive. Agents using these rounds aim for the head and torso wherever possible - hits to the feet and hands won't allow the sedatives to circulate through the victim body.
These are the dealers that they sell these types of ammunition.