This is a 32 round mag for a S&W M&P. It requires only the mag retention notch be cut in order to lock into the Ruger. The other dimensions, including the presentation angle of the follower are compatible from the factory. It is advertised as a 32 round but will not lock in with more than 30 in it. I have not had it to the range yet but I cycled 30 rounds through the gun with no hang ups. Going to be a fun range toy!