The M34 White Phosphorus Smoke Grenade or "Willie Pete" was an chemical grenade manufactured by Rocky Mountain Arsenal used by U.S. forces during the Vietnam War and was also used during the First Gulf War. The M34 WP Grenade was a variant of the M15 designed to be usable as a rifle grenade using the M2 series of grenade launching adapters, and was ribbed to give the fins better grip on the grenade body.