Some possibilities: Glue a neodymium magnet on the back or a piece of wood you can drill into. Maybe you could buy the mounting bolt from Axiom.

How are the M5HPs compared to the M3s?
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A-LFR/1000-8/500v4x2 coming
1000-2,3,1500-3
100,160,QS10x2,800,M5,M3,M50 v4
had v2
Air N2 (someday)