ProMag Walther P99 / SW99 Series .40S&W (20)Rd Blue Steel Magazine.
An extended 20-rd magazine for the Walther P99 / SW99 series of pistols in .40S&W. Constructed from heat-treated blued-steel, with a follower, lock-plate, and base-plate molded from a proprietary DuPont® Zytel™ based black polymer; and using a spring wound from Chrome-silicon wire and heat-treated for strength and reliability.