VDO Betriebsstunden hours minutes count Gauge

Vintage VDO Betriebsstunden Minuten hours minutes counter gauge in used condition. The chrome ring has a dent at 12 o'clock and the lens is good. The total diameter is 6,5 cm, the rear diameter is 5,5, cm and the rubber diameter is 8,0 cm. One bracket mount nut is missing on the rear. The gauge is stamped with “VDO MINUTEN, BETRIEBSSTUNDEN”. Made in Germany. The VDO hours minutes count gauge came from a fire department in Germany with many other “Feuerwehr parts”.