same design as the PF series filterfanssnap fastener developed and patented by Pfannenbergdoor mounting without screws in accordance with VDE 0113 (EN 60204)simple filter mat exchange during operationwith integrated foam seal to enclosuresecure contact due to improved contact springs on the screen griddegrees of protection IP 54 and IP 55, NEMA type 12UR and UL approvalUV resistance (IP 55 version, RAL 7035)cut-out compatible to installation size 4 of the 3rd and 4th Generation