... 1. Quick overviewThese focus lens was made by imported Zinc Selenide material from USA, which are especially designed for laser engrave, laser ... maintanceTo extend the lifetime and working effect, recommend to clean it with alcohal and cotton bud regularly every one month (or ... in stock, after received your final order and payment, you can receive it soon.5. shippmentBy Express(DHL, TNT, FEDEX,etc), ...