This auction is for a Coherent Optics Division optical glass test piece or mirror substrate.  It is Coherent part# 0336-705-00, and is also marked T20WMS02 Test PC.  Would make a nice substrate for your own mirror coating, or also a nice optical diffuser, since it is polished on only one side, and fine ground finished on the other side.

This optic is brand new in the original airtight bag.  As you probably know, Coherent manufactures some of the best quality laser optics around, and you won't be disappointed with this optic.

Be sure to visit my Ebay store, Cheap-Optics, for lots more great deals on mirrors, optics, Newport stuff, and other optical mounts.

Payment by Paypal is preferred, but also cashier's check or money order.