Grenade Carrying Vest

The vest has a carrying capacity of twenty-four 40mm grenades used with M79 and M203 launchers.
Marine Corps Grenadier Set

The Grenadier Set is a suite of three 40mm grenade pouches and one 40mm Grenade Multi-Round System (GMRS) to support the standard combat load for a Marine grenadier. The pouches are Commercial-Off-The-Shelf (COTS) and are part of the Family of Individual Load Bearing Equipment.
Grenade Carrier Vest

The vest is designed to transport the basic load of 40mm grenade ammunition for the grenadier. It is a one-size-fits-all item constructed of very strong nylon fabric and webbing.
MIL-V-43707: VEST, AMMUNITION CARRYING, FOR M79 AND M203 LAUNCHERS
Military specification MIL-V-43707 covers the requirements for a vest for carrying grenades used with M79 and M203 launchers.
MIL-V-44362: VEST, GRENADE, CARRIER (FOR 40-mm GRENADES)
Military specification MIL-V-44362 covers one type and size of nylon duck vest intended for carrying 40-mm grenades.