Jack Williams may like this one!
Williams ? J
20 EOD FLT
I could be mistaken, however I believe this to be associated with the Air Force's 20th Civil Engineer Squadron, Explosive Ordinance Disposal (EOD). Air Force indicates EOD personal are "trained to detect, disarm, detonate and dispose of explosive threats." "Often assigned to some of the most dangerous missions, they perform tactically harrowing and technically demanding tasks in diverse environments worldwide." I suspect with a little research the original owner could be identified.