The pouch was part of the mid-W.W.2 '3 inch mortar carrying equipment', introduced to allow individual soldiers to carry or 'man pack' the 3 inch mortar and it's ammunition more easily. Two of these pouches would replace the 1937 pattern 'basic' pouches on front of the soldiers standard issue web equipment, and in conjunction with a multi pocket backpack, allow the individual to carry half a dozen 3 inch mortar rounds on their body