The Grigorovich MR-3 (Morskoi Razviedchik - 3) was a prototype maritime patrol flying boat built in the Soviet Union during the late 1920s that was not accepted for production.
Data from The Osprey Encyclopedia of Russian Aircraft, 1875–1995[1]General characteristics Performance Armament 2. http://www.all-aero.com/index.php/34-planes/20666-grigorovich-rom-1-grigorovich-mr-3