The Riser to Tank Adapter can be mounted on any flat surface (plastic, plexiglass tanks or concrete risers). It may also be used on corrugated pipe where the rim is flat. Mount with a butyl-based sealant and screw down. It can be used in place of a TAR when the opening is completely inside the inside diameter of the RTT adapter. You may mount a riser, riser safety pan or lid on top.