Per 49 CFR 180.407 (C)

A steel calibration coupon 30.5 cm x 30.5 cm (12 inches x 12 inches) covered with the same material and thickness as that to be tested. The material on the coupon shall have a test hole to the metal substrate made by puncturing the material with a 22 gauge hypodermic needle or comparable piercing tool.

Order includes 1 Rubber, 1 Fiberglass, 1 Epoxy Calibration Plate.

Recommended Spark Tester: Electrotechnic BD-60