I have already ordered an OEM mag for my P99, but I have seen the ProMag's on gunbroker for as little as 16.99 and the OEM mags are 35.00 so I thought if they were well made I could save some $$
I bought two Pro-Mags for my SW99 (S&W variant of the P99) and the only complaint I have with their function is that every maybe 3rd time they don't lock the slide back.
Other than that they feed reliably. And I'm a cheap bastard who uses cheap-ass ammo...