Apr 03, 2021 · Our flat-bottomed EPA vials are easily available in 20 ml, 40 ml, and 60 ml sizes. What makes these vials unique? Flat bottomed EPA vials are made of chemically inert clear Type I borosilicate 33 expansion glass, or for light-sensitive samples, of amber 51 expansion glass. Remember, as with all Pacific Vial glass vials, Caps are sold separately.