It is delivered with a control cable that connects across the main spa packs heater connection circuit board terminals and thus acts as a slave heater which is enegized when the main spa pack's heater is energized. UL Listed USA and Canada. Your #1 Hot Tub Parts Replacement store! The item "Balboa Spa Pack VS501 Aux 2nd Hot Tub Heater" is in sale since Wednesday, May 4, 2016.This item is in the category "Home & Garden\Yard, Garden & Outdoor Living\Pools & Spas\Spas & Hot Tubs". The seller is "hot-tub-parts" and is located in Winnipeg, Manitoba. This item can be shipped to United States, Canada.