Dwyer DDB51 is a non-spring return direct coupled actuator designed for temperature ranges of -22 to 122°F (-30 to 50°C). It has an accuracy of ±5% and operates on 110 VAC or 24 VAC power. The enclosure is made of NEMA 2 (IP42) material and has terminal block electrical connections. It consumes 5.5 VA (DDB) or 7.5 VA (DDD) of power. Standard accessories include imitative baffles, baffle setscrews, and a setting bracket. It fits shaft diameters of 0.4-0.75" (10-20 mm) and has overload protection with a magnetic clutch. The angle of rotation can be mechanically adjusted to 95°, with running times ranging from 66 to 143 seconds depending on the model. It has a visual position indicator, can rotate in both clockwise and counterclockwise directions, and offers manual override via a push button. The control input options vary depending on the model, with DDB offering two-position or floating control, and DDD offering 4-20 mA or 0-10 VDC control. It has a life expectancy of 60000 full cycles and operates quietly with a sound level below 45 dB.