Transformers Various standard configurations of step down transformers designed to power 24 VAC control systems, including thermostats, gas valves, and/or relays. Features: * AT20B Class 2 transformer, phenolic enclosure * AT20B Spud mounting complete with integral attachment screw to secure transformer to junction box. * AT72D NEC Class 2 general purpose transformer. * AT72D1725, Multi-mount (Combination foot, plate or knockout mounting) * U.L. listed and C.S.A. certified PART# PRIMARY TO OUTPUT TERMINATION