Out Of The Blue Artifacts A Library of a lifetime of collecting
Metric Methane Calculator.
National Coal Board N.C.B. metric methane calculator.
Made from plastic and brass with a P.V.C wallet. Size 6″ inches diameter.
It has four revolving calculating discs on the front and one on the back.
Metric Methane Calculator.
National Coal Board N.C.B. metric methane calculator.
Made from plastic and brass with a P.V.C wallet. Size 6″ inches diameter.
It has four revolving calculating discs on the front and one on the back.