Complete kit for easy, professional results! Tranquil Décor Real Basalt columns have unmatched simple beauty. Perfect for creating a bubbling feature in a landscape or indoors, these columns will provide years of enjoyment. Each column is core drilled with 1 1/4″ (32mm) hole from end to end, the last 1 1/2″ is enlarged to 1 3/8″ (37mm) to house optional light ring. Basalt columns are also available individually. Natural top columns make for a beautiful display even if the pump is off.