Natural Basalt columns are attractive natural stones drilled to create overflowing water features. The hexagonal pillars have a sawn base for stability and snapped top that emphasizes the stone. Volcanic basalt oxidizes to form attractive multi-colored patina over time. Atlantic's Basalt Columns are generously core-drilled to 1.375" to fit up to 1" Sch 40 PVC or 0.75" kink-free tubing plus a light cord. A 2" diameter, 5" deep socket at the top recesses Atlantic's Fountain Light and buffers the water plume. Available in single or three piece sets for design flexibility. NBC18 is 18" tall and has an estimated weight of 92 lbs. We recommend using the FB2400 Fountain Basin, FBKIT1 Plumbing Kit, and FP400 Fountain Pump.