Risers Home » Risers Riser Specifications SIZE TYPE OPENING WALLS HEIGHT 24" O.D. Concrete 20" 2" custom 30" O.D. Concrete 24" 3" 2", 3", 4", 6", 12", 18", 24", 36" 32" O.D. Concrete 24" 4" 2", 3", 4", 6", 12", 18", 24", 36" 36" O.D. Concrete 24" 6" 6" & custom 37" O.D. Concrete 30" 3.5" 12", 24", 36"
