The Mid-Continent TS835 is a lighter weight alternative for the PS-835 power supplies. The TS835 weighs only 4.5 pounds while the PS-835 weighs 13 pounds. The TS835 has a battery life expectancy of 10 years. No rewiring or changing of the mounting rack is required when upgrading to the TS835 from the PS-835. Certification of the installation is not affected since TSO'd parts are being interchanged.