Store shells, rocks and other specimens in these Archival Over-Wrapped 35 pt. Chipboard Specimen Trays (250-Pack). Made from quality unbuffered white chipboard, the trays are over-wrapped with an acid-free paper. During a 4-year test period, the pH of the chipboard averaged 7.9, with a range of 7.2–8.7. The trays are completely white to best display specimens and to reveal frass and other pest evidence.