The inside solid design is used where the case flange is part of the compressor and not supplied with the packing case. Normally the Type 65 assemble replaces a braided or soft packing. AAVOLYN engineers can utilize this design to upgrade your reciprocating compressors or pumps to mechanical packing where you may presently be utilizing a soft packing style of seal. The case will work with the existing flange and greatly extend packing life while eliminating rod wear.