From Brotato Wiki
Medical Turret is an in-game item that can be bought from Shop or can be found in a Crate. Most Items increase the Stats of the player while some of them provide unique effects.
Buying the item spawns a Turret at the beginning of each wave that shoots healing projectiles towards you while you are within 400 range for 3 + (5% ) healing every 2.2 seconds.
Note that the engineering scaling rounds down. So it takes 20 or more engineering for the turret to heal 4 HP. While it only takes -1 or more engineering for it to only heal 2 HP per shot. So think twice about buying Ritual if you have a medical Turret on a non engineering build.
The Medical Turret is a Structure and is unaffected by Primary Stats, such as Damage, Life Steal, Attack Speed, Crit Chance. But is affected by Engineering.