These disposable plastic cassettes hold tissue specimens during processing and embedding, as well as in storage. Molded from a special high-density polymer, they keep specimens safely submerged in liquid and are totally resistant to the chemical action of histological solvents. The efficient flow-through slots maximize fluid exchange and ensure proper drainage. This new model differs by the special hinge that holds the base and cover together. This hinge allows cassettes to be opened and closed as often as necessary. The cover can be removed and re-inserted easily without danger of specimen loss.