Leak tight to 1 x 10-9 atm-cm3/sec He. Hazards - Very toxic. Tolerances: thickness (+0.005mm -0.002mm), width & length ±0.25mm To maintain Vacuum tightness store and use in a dry atmosphere below 50% relative humidity. Typical analysis ppm: BeO 130, Fe 180, Al 10, Mg 10, Si 80, C 200, Cr< 10, Co<5, Cu 10, Pb<1, Mn 30, Mo<10, Ni 50, Ca<10, Zn<50, Ag<1, Ti<10. **End Use Statement required prior to shipment** This item may require a 'standard individual export license'. Please allow 10-20 days for this process.