AS-R13 Septic Tank Riser kit - 24" Diameter X 13" The NEW standard in septic tank riser safety & FREE SHIPPING Includes: safety barrier, riser, cover, mounting fasteners, sealant, and illustrated instructions. Plastic adapter ring is 29"x 29" with a 24" riser ring inner diameter. Complete and ready for installation A septic tank riser makes installation of the Aero-Stream Remediator easier and even faster. Low profile cover adds only 1/2 to the riser Green structural foam HDPE Four (4) Stainless Steel Square Bit Screws attach Cover to Riser Ring Compressible rubber gasket Virtually flush with the lawn Easier mowing and maintenance manufactured from durable HDPE.This  material wont degrade and crumble like concrete riser pipe. Double-walled corrugated with 23.5 ID smooth inner. Provides additional safety barrier below the septic riser cover Tank can be pumped without removal Removable for servicing baffles Fits all opening shapes e.g. round, square, rectangular, etc.