APC Smart-UPS Ultra 1U RM Lithium-Ion Battery Pack (SRTL50RMBP1U-LI). Compatible with APC Smart-UPS Ultra rackmount models such as SRTL3K and SRTL2K2. Provides reliable backup power for critical IT infrastructure. Designed for 1U rack installations, this lithium-ion battery pack offers long service life and reduced maintenance compared to traditional battery chemistries. Manufacturer: APC by Schneider Electric. UPC: 731304414377. Replacement battery pack for Smart-UPS Ultra systems; standard 5-year repair or replace warranty per manufacturer terms.