The Exo Terra Flextray can be used to hold substrate and/or contain liquids inside the Flexarium (available in vertical and horizontal models).

PT2572 -  Flextray C use with Flexarium 38 (vertical)

PT2573 - Flextray D use with Flexirium 38 (horizontal) and Flexarium 65 & 100 (vertical)

PT2574 - Flextray E for use with Flexarium 65 (horizontal)