No thumb strap on any of my DeSantis IWB or OWB holsters. The M&P fits these holsters perfectly and there is a tension adjustment screw if you want a tighter or looser fit.

For practice I shoot Winchester 9mm luger "white box" FMJ 115 gr or Winchester 9mm luger "Nato" FMJ 124 gr rounds. When I carry I load the Winchester PDX1 bonded JHP 124 gr rounds.

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Jeff Lynch
Sugar Land, Texas