Grip Plus 2-Magazine Adaptor

Along with a S&W 6906 (Police Trade-In), came two magazines.These are unique, in that they are stainless model 59 (14 shot) type mags with a plastic piece fit to the mag as to contour to the grip and give comfortable feel, along with the increased capacity over the standard 12 shot mag for the 6906.Where can I find more of these??SUPPORT THE NRA!