(From the Squadron supplier:) For the 25FS history, see the details listed above. Not sure what SED stands for, but the ‘RATS’ are the ‘LINE RATS’ which are the maintainers that hang out in the “Line Shack” working on just about everything on the airplane you can think of!! This patch was found in a Korean embroidery shop in VERY limited quantities and does not come with velcro attached!