Could be an old version or there could be different types and sizes of thermite grenades
Incendiary Grenades
The AN-M14 incendiary (thermite) hand grenade is cylindrical in shape and has a sheet metal body with emission holes in the top (fig. 12-4). It weighs 32 ounces and contains a filler of 26.5 ounces of TH3 thermite mixture. It uses an igniting fuze that sets fire to the thermite filler after the normal delay. The thermite filler bums for approximately 40 seconds at a temperature of about 4300°F. A portion of the thermite filler changes into molten iron that flows out of the grenade and produces intense heat over a small area. This molten iron ignites or fuzes whatever it touches. It is used to ignite combustible materials and to destroy all types of equipment. It burns through about one-fourth inch of steel and welds together steel or iron machinery parts when molten iron flows between them.