I have fitted this as minimally as possible to my Non OR M&P. I sold it and swapped it over to my OR M&P and it is a lot tighter than the Non OR, probably needs another small bit of fitting.
Should be GTG on other M&P's, though may need the same bit of fitting.
150 rounds through the barrel and comp, worked great with 115gr S&B with stock recoil spring.
Thread protector included.
You can see some of the black sharpie still on the barrel where I fitted it.
This is for a 4.25" gun and fitted to a 2.0. I don't know if the APEX are backward compatible to the 1.0's. I believe the comp is not.
Asking $200 shipped. Payment by Discreet paypal Gift or Zelle.