Canon Command Back 90: (Battery: 1-CR2025) For use with T90. Records data and offers various types of control for timed photography. Auto ISO exposure control. Data options: Date (up to year 2029), day/hour/minute in 24 hour format, 6 digit number, letters A-F, frame counter up to 4 digits. Timer options: self timer, interval timer, long release timer, frame counter setting (camera stops shooting after a pre-determined number of exposures have been made). Data displayed on LCD monitor panel.