You know how Seiko utilizes the 10mm fitting butting (spherical center) on it's lenses. Do all 1.67 Hi-Index basically do this? If it came down to using Poly or 1.67 which would you do? Does that center actually make the difference. And don't tell me about Poly and ABBE (Mike DiSanto's Poly article changed my thinking). Remember, cost for us is a factor and we all know Poly is cheaper for us to get. Let's say the customer has a , umm...-6.00 lenses.