Replace the Smith & Wesson M&P 9/40 magazine base plate with a rail adapter so you can attach the MantisX to your  M&P 9/40.  

Preferred if you don't have light-accommodating holster and want to train with holster draws, or if the firearm doesn't have a rail.

Not compatible with 10 round magazines.
Not compatible with M&P 2.0 magazines.

Part number:  MT-2059