Marksman identifies enemy targets at a longer range by showing their player names at a greater distance. The Pro version allows for longer hold breath period, doubling the player's hold breath time from four seconds to eight seconds, similar to the perks Iron Lungs and Scout from previous games. This works very well for sniper rifles, allowing a player to keep the scope's reticule steady for a longer time, but even if the player is not using these weapons, the Thermal Scope also benefits from the Pro effect as well as the Breath proficiency.
The Pro version is unlocked at 50 kills while using Marksman and holding breath. The effects of Marksman are however, canceled out by Assassin Pro. The Breath proficiency can be helpful in going for completeing the Marksman perk challenges.
Marksman returns in Call of Duty: Infinite Warfare. It lets the user acquire enemy names from a greater distance and reduce flinch on sniper rifles but gives a very minor benefit to other weapons. It is unlocked by Level 11.