The weather protection grid, System 623V IP23D, from MLL Hamburg, is a ventilation grid made of aluminium with a free ventilation cross section of47%. The shape and arrangement of the slats largely prevent ingress of rain and snow. The IP23D protected MLL ventilation grid is penetration safe against wires. On the reverse, there is a fly screen made of stainless steel as protection from insects and small animals. For attachment and protection against unauthorised removal of the weather protection grid, various fastening possibilities are provided. This system is penetration safe, spray water protected and prevents access with wire according to DIN EN 60529:1991+A1:2000. The system 623V_IP23D is equipped with a penetration safe V-slat of the medium series of type 020V in the clamped Frame 603. The ventilation grid with protection class IP23D is superbly suited for installation in doors.