End-of-service alarm lets you know if the unit has sacrificed itself to protect your connected equipment and needs to be replaced. Great for use with refrigerators, microwave ovens, treadmills, and garage doors.
Have used TrippLite power conditioning products since 1980's and UPS's since mid 1990's in broadcasting/recording studio tech situations. Never ever any problems. Needed these for several devices that didn't justify UPS's but needed surge protection.