An electronics housing system adapted for electronic devices of the type including a main chassis unit and at least one removable module mountable with the main chassis unit for supporting electronic circuitry components electro-optically coupled within the main chassis unit, comprising: - the removable module having a main body including two opposing mounting edges (14, 16) and a connection edge; at least one of the mounting edges of the removable module including an opening to vent a cooling air flow into an interior cavity of the main body of the removable module from the main chassis unit; - the main chassis unit having a pair of separated and opposing mounting assemblies (24, 26) adapted to receive and secure a removable module between the opposing mounting assemblies (24,26); at least one of the pair of the opposing mounting assemblies (24, 26) including a plenum means having an opening for communicating the cooling air flow into the removable module; - the at least one of the pair of mounting assemblies (24, 26) of the main chassis unit further including a seal plate member having a base plate for securing to the at least one of the pair of mounting assemblies (24, 26) and an affixed elastomeric and resilient seal member surrounding an opening formed through the base plate and extending from a surface of the base plate, the seal member forming a sealing air dam about the cooling air flow communicated through the plenum of the at least one of the pair of mounting assemblies of the main chassis unit; - the at least one of the pair of mounting assemblies (24, 26) of the main chassis unit including a pair of guide rails (42a, 42b) extending from the mounting assembly of the main chassis unit forming a U-shaped channel between the pair of guide rails for receiving at least one of the mounting edges (14, 16) of the removable module. the at least one of the mounting edges of the removable module further including at least one cooperating guide rail to protect a sealing surface from damage and is adapted to abut against one of the mating guide rails extending from the at least one of the pair of mounting assemblies (24, 26) of the main chassis unit when the removable module is mounted within the main chassis unit, wherein the removable module further includes latch means for clamping the at least one cooperating guide rail of the removable module to at least one of the guide rails of the at least one of the pair of mounting assemblies (24, 26) of the main chassis unit for providing a fixed structural boundary condition between the removable module and the chassis unit. - the removable module having a main body including two opposing mounting edges (14, 16) and a connection edge; at least one of the mounting edges of the removable module including an opening to vent a cooling air flow into an interior cavity of the main body of the removable module from the main chassis unit; - the main chassis unit having a pair of separated and opposing mounting assemblies (24, 26) adapted to receive and secure a removable module between the opposing mounting assemblies (24,26); at least one of the pair of the opposing mounting assemblies (24, 26) including a plenum means having an opening for communicating the cooling air flow into the removable module; - the at least one of the pair of mounting assemblies (24, 26) of the main chassis unit further including a seal plate member having a base plate for securing to the at least one of the pair of mounting assemblies (24, 26) and an affixed elastomeric and resilient seal member surrounding an opening formed through the base plate and extending from a surface of the base plate, the seal member forming a sealing air dam about the cooling air flow communicated through the plenum of the at least one of the pair of mounting assemblies of the main chassis unit; - the at least one of the pair of mounting assemblies (24, 26) of the main chassis unit including a pair of guide rails (42a, 42b) extending from the mounting assembly of the main chassis unit forming a U-shaped channel between the pair of guide rails for receiving at least one of the mounting edges (14, 16) of the removable module. the at least one of the mounting edges of the removable module further including at least one cooperating guide rail to protect a sealing surface from damage and is adapted to abut against one of the mating guide rails extending from the at least one of the pair of mounting assemblies (24, 26) of the main chassis unit when the removable module is mounted within the main chassis unit, wherein the removable module further includes latch means for clamping the at least one cooperating guide rail of the removable module to at least one of the guide rails of the at least one of the pair of mounting assemblies (24, 26) of the main chassis unit for providing a fixed structural boundary condition between the removable module and the chassis unit.