The document provides an overview of the UL 1449 Third Edition standard for surge protection devices (SPDs). It discusses the changes from the previous standard, including introducing new SPD types (Types 1-4) based on location within the electrical distribution system. It also covers new testing protocols that use six times more energy and new voltage protection ratings (VPRs) to replace suppressed voltage ratings. The document discusses SPD product lines from Advanced Protection Technologies that are compliant with UL 1449 Third Edition.