A tactical shotgun assembled from different modules. The muzzle of the shotgun has a faceted shape with holes for cooling. The TACT shutter. The SHTR21 is made of lightweight metal material, which also makes the weight of the weapon itself much lighter. There is a picatinny rail module of the bracket type on the main body. The butt and handle are made of sturdy plastic.

Camouflage was applied layer by layer to the main part of the hull with different types of paint and methods of its application. In some places, the paint has already worn off due to the frequent use of this weapon.