Thanks for the response Graham. The reason I asked is because a buddy of mine is shooting with an Alexa Mini and M15 but had no base plate. He wanted to use my Movi Pro baseplate. I will pass the information along.
I think your top plate would work, or he could try his own top plate in a pinch, which is the same as the one on the Movi Pro. On the M15, the Top and Bottom plates are sort of interchangeable, but I always did the opposite: Used an extra bottom plate as the top plate on the M15. The bottom plate is wider and has more hole options.
Gotcha, I never used the M15 as I started with a Ronin and Ronin-M before switching to Freefly, so as far as knowing the M15 accessories I am clueless. I do have the Cinemilled Movi Pro baseplate, but that still may not work on the M15 due to the dimensions.