PowerPact B-frame circuit breaker accessory, LV426921, offers proven performance, flexibility and reliability. For all types of PowerPact B-frame circuit breakers that use uninsulated power connections, the minimum clearance distance between the enclosure backplate and uninsulated power connections. When using uninsulated connectors be sure to maintain the proper clearance between live parts and the grounded metallic back pan or use the insulation screen. These screens come in set of 2.