A Counter Insurgency Support Office (CISO) manufactured black sweater with V-neck. A green example can be found here. These would have come under the auspices of Ben Baker, Deputy Chief of the U.S. Counterinsurgency Support Office (CISO) and have been part of the various sterile unform and equipment items produced in Japan to support SOG.
This example belonged to Frederick Howard who served in MACV-SOG from March/April 1968 at Forward Operational Base #1, Phu Bai. He joined Recon Team New Jersey and took the 1-2 position with Ronald Zaiss the 1-1 and Richard Gross the 1-0. Howard later held the Assistent Team Leader (1-1) position until July/August when he was reasigned to the Tactical Operations Centre (TOC), Communications Section. Pictures can be seen below of the veteran wearing the sweater in Vietnam.
Originally sourced via Jason Hardy