[5] The design was later repurposed as a white phosphorus smoke round for marking, signaling, and screening purposes.
[6] Officially designated projectile, 155 mm howitzer, M110, the original round was a 26.8-inch (68.1 cm) steel shell with a rotating band near its base and a burster rod down its center.
To distinguish between the two, the HD versions were gray marked with two, horizontal, green bands, like most other chemical artillery shells.
The WP versions were gray with a single, horizontal, yellow band, as is standard for military smoke munitions.
Remaining stockpiles of the HD version are in the process of being destroyed in accordance with the 1997 Chemical Weapons Convention.