The transformers are available in 40VA, 75VA, and 100VA. A switch / circuit breaker is provided for each transformer and on “B10” models a switch / circuit breaker is present for controlling power for the entire unit. An LED indicates the presence of 24 Vac on the Class 2 terminals on the outside of the enclosure, or wires on the inside. An internal high-voltage wiring compartment and two 120 Vac grounded convenience outlets are provided on most models. Each power supply series is available with a number of various options.