Smooth bore, curved angle firing mortar with a 120 mm M74 (M75) shell 

Mortar:

- used in the open area, trenches, rear slopes, elevations, depressions to eliminate personnel on the ground, open routes through barbed wire and silence the firearms;

- open routes through engineered barriers;

- designed to protect troops from enemy fire and surveillance, create smoke screens, and illuminate the area.

NSB-4 sight device is used for firing.

M62P3 120 mm fragmentation, smoke screen, and illumination projectile is used to fire from the mortar.

NSB-4B is designed to aim 120 mm M74 and M75 mortars.