Dynatron 40x40x10mm 3pin 12V Dual Ball Bearing Fan (5500 RPM) The Dynatron DF124010BM-3G is a medium speed 40 x 40 x 10mm Dual Ball Bearing Fan. Designed to use as a case fan, this fan operates on 12V DC and uses a standard 3-pin power connector (with tacho signal lead). Its dual ball-bearing design ensures durability and long-life. 40x40x10mm size compatible with a large array of compact computer cases including many Mini-ITX enclosures e. g., M350, Morex 557. 4 self-tapping screws included.