The IVAC MEDICAL SYSTEMS 501 SERIES ECG MONITORS Replacement Battery is replaced by the UB12260 manufactured by UPG - Universal. This 12 volt battery has an amp hour rating of 26ah. This state-of-the-art lead-acid battery is sealed and maintenance-free, which fixes the acid electrolyte in a gel or in an absorptive fiberglass mat for maximum performance. The advantage of this design is that the battery needs no water additions, can be operated in any position, and can be used in close proximity to people and sensitive equipment. This battery may or may not be the original OEM battery for your equipment, but a compatible substitute that is designed to meet the original battery's specifications. Trust Battery International for all of your battery needs.