The 17896 is a cable that is used to connect the TGA electronics to the position 2 laser connector on the TGA100A dewar. The 17896 is still available as a replacement part. All TGA100As included the 17895 cable for the dewar position 1 laser. For a TGA200 running lead-salt lasers in positions 1 or 2, the 21954 or 22001 cable should be used, respectively. If a TGA100, TGA100A, or TGA200 has been upgraded to use a thermoelectrically cooled (TEC) laser, there is no need to use a dewar laser cable. The TEC laser module has its own cable attached.