The Outline SUB118 Passive Subwoofer is a high-output sub-bass system fitted with one long-excursion 18” transducer. It is intended for applications requiring powerful low-frequency delivery, including live music and dance venues. Outline E.R.P. (Energy Retentive Porting) design assists airflow, reduces internal turbulence and supports transducer efficiency. The enclosure uses Baltic birch plywood with a black polyurea coating and includes threaded installation and pole mount points.