The DORMA DEM500HA electro-magnetic door holder for floor, ceiling or wall installation, supplied with manual release button EM 500-H x 150/175 mm. Can be mounted to floor, ceiling or wall & can be wired on to building control systems. 24V DC hold-open magnet with pole reversal protection and integral test pushbutton for floor, ceiling and wall mounting. Holding force 490 N. Generally approved by the DIBt-Berlin for use in hold-open systems (in Germany). (System acceptance inspection may be necessary.) Suits fire activated door closing. This model 150/175 mm.