The Edco HSP121BT 1RU is an advanced 3 stage hybrid, solid state power line protector. Features such as noise filtering, common mode and normal mode suppression, nanosecond reaction time, power line tracking, and compression screw terminations, make the Edco HSP121BT 1RU an excellent choice in commercial and industrial applications. The Edco HSP121BT 1RU offers a replaceable fuse designed to remove the load protected equipment from the line if the unit is either overloaded or the internal protection fails. This feature prevents surges from entering equipment through a failed protector, not noticed by the user. Unlike models with only an indicator, which may take weeks to notice, the Edco HSP121BT 1RU demands immediate attention upon the unlikely occurrence of internal failure.