CheaperThanDirt.com and ProMag.com offer aftermarket LC9 10-round magazines for sale. ProMag manufactures the clips that both retailers sell, however, the price is considerably lower at CheaperThanDirt.com, as of 2015.
Sturm, Ruger & Co. manufactures the LC9 compact semi-automatic pistol. It comes standard with a 7-round magazine and a 9-round clip is optional. ProMag.com makes an aftermarket 10-round magazine for the LC9. It is made of heat-treated blued steel with a base plate made from DuPont Zytel polymer. This clip does not work in the Ruger LC9s striker fire pistol. ProMag.com magazines are made in the United States and come with a lifetime warranty against manufacturing defects.