PWD-4W and PWD-2W fan units are intended for assembly to 380 x 380 mm openings which are located in the top plates of SZB IT and SZE2 PC cabinets. The PD-2W fan unit can be assembled to the 380 x 210 mm opening in the top plate of 1000 mm deep SZB IT cabinet. In the standard version, the units are equipped with 2 or 4 fans, an illuminated switch and a fuse.