RARE!! 308th Tactical Fighter Squadron "Emerald Knights" USAF Patch - Vietnam.  Patch is in good condition and was uniform worn with the hook and loop still on the back of the patch.  Not certain but looks to be the older version from around the Vietnam war era.  Measures about 4.25 inches from top to bottom and about 3 inches side to side.  See photos for additional details or feel free to ask any questions you may have.