Dark blue wool with applied scarlet wool crossed hammers construction.

The name artificer means one who works with arms and weapons. The U.S. War Department created this rank as a result of the Spanish American War. Infantrymen who wore the crossed hammers were known as artificers while their artillery counterparts were mechanics and artificers. Those that  were designated as artificers wore this cloth with crossed hammers on both sleeves in the same location as other chevrons. The crossed hammers were made in the basic branch colors for Infantry, Artillery, engineers, and ordnance. The patterns were actually cut out of wool material with steel dies for uniformity. 

This originates from an established collection of U.S. Army chevrons