4 inch (100mm) X-cut lithium niobate wafer from Crystal Technology (now G&H (Gooch & Housego)). 

Both sides are polished. 0.7mm thickness. See the diagram for crystal axes. Laser marking on the +x face under the major flat.

These are un-used new wafers from liquidation of a closed optoelectronic company. They were for waveguide substrate for PPLN and electro-optic components.

Datasheet available on G&H website.

Packed in individual wafer boxes as shown. Package has been opened outside clean room.