This Tuf-Tite 12x12 Septic Tank Riser is 12'' in diameter and 12'' tall. Tuf-Tite risers are stackable giving great flexibility when bringing your access to grade. Each riser locks into position and is fastened with stainless steel screws. The 12'' Tuf-Tite Risers fit all 12" risers mad by Tuf-Tite. Tuf-tite 12x12 septic tank riser.