The range of toroidal transformers can vary in terms of power capacity, voltage, and mounting style: Power capacity: Standard toroidal isolation transformers can range from 100 to 5,000 VA. Voltage: Dual primaries can be configured for 120 V or 240 V operation. Dual secondaries can range from 2 to 12 V windings to 2 to 120 V windings. Mounting style: Standard mounting for sizes up to 5000 VA is with a single metal centering washer and mounting screw or bolt. Other mounting methods include PCB mounting, DIN rail mounting, and resin center potting with brass inserts. Toroidal transformers are known for their high efficiency, typically ranging from 95% to 99%. This high efficiency is due to their near-ideal design, which effectively contains the magnetic flux within the windings, eliminating leakage flux.