W. Va. Code § 22A-2-56: Checking systems.

Each mine shall have a check-in and check-out system which will provide positive identification of every person underground and will provide an accurate record of the persons in the mine kept on the surface in a place that will not be affected in the event of an explosion. Said record shall bear a number or name identical to the identification check that is securely fastened to the lamp belt of all persons underground. The identification check shall be made of a rust-resistant metal of no less than sixteen gauge.