[Trifocaltrev]

Electrical Strength Unit In Air In Oil
0.127mm ±10% kV/mm 14 74 - 78
0.18mm ± 10% kV/mm 14.5 70 - 88
0.25mm ±10% kV/mm 13.5 68 - 77
0.30mm 10% kV/mm 12 60 - 74
0.40mm ± 10% kV/mm 10.5 52 - 63
0.50mm ±10% kV/mm 10.5 50 - 53
0.80mm* ±10% kV/mm / /
1.00mm* ±10% kV/mm / /

Looking at the data sheet for Elephanthide 4, it comes in the above thickness ranges, if you mic it up with a metric micrometer you should be able to get the nearest thickness to the original.

Regards
Trevor.