https://www.diyaudio.com/community/threads/f5m-kit.408290/
From Nelson Pass on chassis: The 2U was my default on bench test specs, biased at 1 amp. Sink was warm, but not hot.
Dissipante 02/400B 2U 120 euro 300B 103 Euro
03/300B 3U 126 Euro 03/400B 3U 142 Euro