Although I was skeptical that this was going to help my old Roomba, it works perfectly! My Roomba 551 is quite old & has been a reliable helper for years (I am 72 yrs old) but the original battery would only charge enough to run for 15 minutes! I thought that I would need to say goodbye to my old friend & helper. I looked for a new battery & found the longer life battery. It was easily replaced & my Roomba was off like a shot. I pushed the docking button & it immediately docked perfectly & began charging. I am absolutely thrilled. My lovely robot has new life! The next day however, my Roomba (on the docking platform) began flashing orange/red! I was afraid that it was due to the new battery. I checked the wheels, the brushes etc. but I am not sure why it happened. However, as of now, 2 weeks later, it is working just fine & will run for more than an hour! No more red flashes, no errors & my floors are free of dust, dirt & dog hair. I may one day, replace my old Roomba but as of now, this battery did the trick! BTW, Roomba customer service is fantastic! I spoke with a young man who was courteous, helpful & a font of information.