Hammond's 166 series transformers are designed for economical single primary applications. These transformers feature an open style, channel bracket, and two-hole chassis mount, with minimum 6" long leads. The dual bobbin design eliminates the need for electrostatic shielding, and Class B insulation (130 degrees C) provides extra protection. They are UL listed and CSA certified, making them suitable for a wide range of industrial and commercial applications. The 166E20 specifically offers a low voltage filament design for various power needs.