Joejosh999
The following physical dimensions are taken from a page on the L3Harris website for the FA2100 series of L3Harris Cockpit and Data Recorders:
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Height: 5.5 in. (13.97 cm)
Width: 5.0 in. (12.70 cm)
Depth: 12.6 in. (32.00 cm)
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In an accompanying image, the CSMU is the drum-shaped component of the FA2100 series assembly. From that image, my reckoning is that the dimension of the CSMU portion is approximately 100mm OD x 100mm (4" x 4") tall.
For perspective, look for a 1L / 1 Qt deep stainless steel mini sauce pan in your kitchen cupboard.
If my size estimate is correct, then the CSMU component that KNKT is searching for is somewhat smaller in diameter and height than such a sauce pan.