The M34 had a segmented body to allow for a better hand grip and to identify it as a casualty-producing grenade, even though fragmentation was not its primary damage mechanism.
[2] The M34 had a prescored cylindrical steel body with a conical base designed for compatibility with the M1 rifle grenade adapter using M195 blanks for the M7 launcher or any 22mm NATO diameter rifle/carbine barrels.
It contained 15 ounces of white phosphorus with a small bursting charge to rupture the body and dispense the WP, which would ignite when it came in contact with air.
It could not be thrown as far as fragmentation grenades owing to its weight and stray burning WP gobs and particles could be blown back on friendly troops.
Grenades manufactured prior to the adoption of NATO STANAG 2321 in 1987 (which standardized ammunition color coding for rounds larger than 20mm) had a light gray body, yellow band, and black markings.