These Power Distribution Blocks are Listed to the Power Distribution Block Standard UL 1953. They contain the same features and characteristics as the non-Listed blocks however, these have spacing's that are suitable for installations in most industrial control panel feeder and branch circuits, HVAC systems, and Wireways (with optional cover; sold separately). They are available in one, two, or three pole configurations. An Adder is also available with optional End Barrier (sold separately), to allow user customized configurations.