EnhanceAir™ PRO Diffuser Rings by Complete Aquatics Liquid The EPDM rubber membrane is

The EPDM rubber membrane is wrapped around a hollow plastic tube

Nessler's total ammonia test will give false

Hidden Styrofoam ring for stability and flotation

and includes the following components (left to right in the image) as well as instructions:

Kit Includes: EnhanceAir™ 3/8" x 20' Self-Weighted Air Line

EnhanceAir™ PRO Diffuser Rings by Complete Aquatics Liquid The EPDM rubber membrane isThe EnhanceAir PRO Diffuser Ring has a unique 360 ring shape that improves water circulation and a raised design that provides maximum efficiency. This self weighted diffuser includes a back flow check valve and attaches to EnhanceAir PRO Self Weighted Air Line or other 3 8" self weighted air line. The base plate keeps the diffuser away from rocks, gravel and bottom debris. SKU UPC Code Description Dimensions Air Flow Range AE40121 653341177193 PRO