If you buy the cheap plastic film holders on eBay, remember that someone may have been getting rid of them because of light leaks. You can test them at least two ways. You can wait for the leaks to show up on that really important picture that has now gone bad or you can try test #2 and discard the junk. I loaded mine, waited for a really bright day, laid them out in the sun for 1/2 an hour, trying both sides up for 15 minutes, numbered the film holders, then shot a white sheet of paper with the same number on it in the really bright sun. The film holders that past that test have worked very well with normal protection.

John