Personnel from the 25th Infantry Division served in Vietnam between 1963 and 1971. Their shoulder sleeve insignia featured a yellow lightning flash in the middle of a red taro leaf. The taro plant is closely associated with Hawaii and reflects the 25th's Hawaiian Division lineage. The lightning bolt was designed to represent the manner in which the Division performed its assignments and lead to its nickname "Tropic Lightning".1
1. The Institute of Heraldry