You have successfully added from to your part list.
Foil Integrity: Foil is available in three classifications of integrity:
Vacuum Tight: no detectable leakage through the foil when tested with a helium mass spectrometer leak detector, sensitivity of 1 x 10-9 atm-cc/sec. o Optically Dense: not be penetrated by light when tested by illuminating one side of the foil over a restricted area with a high intensity light source, and viewing from the opposite side in a darkened room.
As-Rolled: supplied in as-produced condition, not inspected or guaranteed to be vacuum tight or optically dense.