I am not very knowledgeable on aviation equipment but I purchase a few sets off of a retired pilot and they have been sitting in the cases for a while. I wiped them down and put batteries in them and light turns on . I don’t really have the means to test them fully but I am selling them as a used pair as is . The pad for the ears and the head will need to be replaced because they are starting to fall apart. I looked it up and you can buy a new set of factory pads pretty inexpensive. Thank you