I have just bought a pair of Pitboss II sunglasses at half price. Replacement lens are rare and I am surprised to find them on eBay. It is so cheap that I do not have confidence in its quality.
http://www.ebay.com/itm/ZEISS-Lense...479?pt=LH_DefaultDomain_0&hash=item3f3793eaff
http://www.ebay.com/itm/ZEISS-Lense...479?pt=LH_DefaultDomain_0&hash=item3f3793eaff