This is the factory Kel-Tec PF9 9mm 7-round magazine. 

Here is some information about the Kel-Tec PF9.

One of the lightest and flattest 9mm pistols ever made, the PF-9™ is also one of the most concealable. This semi-automatic has a double action only firing mechanism, with an automatic hammer-lock safety. Developed from our highly successful P-11™ and P-3AT™ pistols, it retains many of their best features. Of course, as concealable as the PF-9 is, others won’t see them.