Tubular High Pressure Sodium HPS with ignitor lamps are availabe in 50 Watt, 70 Watt, 150 Watt, 250 Watt and 400 Watt. Brand references to these are Osram NAV T, GE Lucalox T, Philips Master SON T and Sylvania SHP T. When selecting SON T lamps please take care to check if you need Internal ignitor or external ignitor, these are differentiated by a trianlge with an E inside (external ignitor) and an I inside (internal ignitor).