SEM 7800 Series are heavy duty, electrically controlled door holding magnets. Magnets are fail safe and hold until the current is interrupted. A manual door closer is used to control and close the door. • Surface wall mounted • Powder Coat finish • Tri-voltage design with 35lbs. of holding force • UL listed for smoke barrier or labeled fire doors • Tested and certified under ANSI Standard A156.15. • Shipped with die cast housing, cover, armature and WMS screw pack. • 24/120 ACDC