Master trooper

Master trooper is a rank used by several state police agencies within the United States and in some world militaries.
In particular, in the Louisiana State Police, in the United States, it is a rank below sergeant, yet above senior trooper. The insignia for this rank consists of a gold colored 'MT' collar pin worn on the wearer's right lapel. Troopers who complete 15 years of satisfactory or exceptional service are promoted to the rank of master trooper. The title of address is "master trooper".
Usage in other agencies or countries may vary. The rank of Master Trooper is used by the following state agencies within the United States: