Josh's Frogs Substrate Barrier is a vital layer in all successful naturalistic vivaria. Substrate Barrier fits between the false bottom and ABG Mix layers, and ensures that no ABG Mix falls down into the false bottom, disrupting water flow. Josh's Frogs Substrate Barrier also prevents a clogged false bottom and the wicking of water from the false bottom into the other naturalistic vivarium substrate layers. When these substrate layers become saturated, anaerobic bacteria grow, which create a smelly, very unhealthy environment. The only solution is to replace the affected naturalistic vivarium substrates with new ones. Josh's Frogs Substrate Barrier is simple, inexpensive, and effective way to prevent this situation from happening. Each peice of Josh's Frogs Substrate Barrier measures approximately 18" x 24"