Sig Sauer P229 10 RD .40 S&W or .357 Sig Mec-Gar Magazine MGP22910B. 

Constructed from certified carbon steel and features a heat treated housing and high-impact polymer or certified carbon steel follower and floorplate. The magazine spring is made of high strength type "D" music wire-the strongest wire available. TIG welding provides additional strength and a seamless finish. Each magazine surface is specially treated to ensure high corrosion resistance.

Mec-Gar is proud to be the Original Equipment Manufacturer of magazines to most of the prominent firearm manufacturers for the last 40 years including AMT - Armscor - Astra - Beretta Bernadelli - FN Browning - BUL - Charles Daly - Colt - CZ - IMI - Kel-Tec - Kimber - Llama - North American Arms - Remington - Sigarms - Smith & Wesson - Springfield Armory - STI - Standard Arms - Star - Steyr - Tanfoglio - Taurus - Walther