The 21954 is a cable that is used to connect the TGA electronics to the position 1 laser connector on the TGA200 dewar. The 21954 is still available as a replacement part. TGA200s that have a laser in the dewar's position 2 also use the 22001 cable. For a TGA100A running lead-salt lasers in positions 1 or 2, the 17895 or 17896 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.