I do not know the answer to your question but I would suggest that you tell those who have the drone which particular screws you are interested in, there may be various sizes of 'hex' used in the drone. However I would almost guarantee that they are metric and not imperial.
Secondly, if these are small screws with small heads and even smaller 'openings'/sockets, it might an idea to use a magnifying glass to verify that these sockets are in fact pure hexagonal. There is an alternative style of socket known as "Torx", imagine 6 toothed chain sprockets. In the smaller sizes it can be difficult for ageing eyes to, unaided, distinguish between hexagonal sockets, intended for Allen keys/bits, and Torx sockets.