very low quality slides. They are plastic sliders and true to size. The cardboard boxes they come in are typical of paper boxes and wear out quickly with frequent use. And because they're smaller, you won't be able to find replacement foil cases for them. Since they're too small, you can't mount them properly on the mech stage either. The samples themselves are of poor quality with very little detail. They really shouldn't be watched more than once. For almost the same price, Revain has several 25-piece slide sets that are far superior in quality. I strongly recommend everyone to study one of these instead. You get fewer slides, but these are slides that are really worth checking out.