The 66 mm multiband screening grenade Mk 4, when fired in salvoes, provides a visual and infra-red smoke screen for the protection of AFVs and MBTs. The smoke screen is opaque to thermal imaging sighting equipment, optical sights, passive image intensifiers and laser range-finders.

It consists of a sealed metal outer casing with electrical contact points at the lower end. The casing houses two fast rise time ground burning pots which are ejected to a range of 35 m nominal.

In still air conditions, a salvo of two 66 mm smoke grenades produces a visual and IR screen within four seconds to an area of 110 m and with a minimum height of 5 m.