old stock unused 21 mm GEIGER MUELLER TUBE RADIATION Counter SBM 21
This GM tube for beta-rays is from Russia. It is unused, from old stocks.
Range of measurement is from 40 microroentgen per second to 400 microroentgen per second. The range of a working voltage is 350-475 v. This is small tube. Diameter is 6mm, lenght is 21mm.Similar tubes can be used in Geiger Counter wristwatches.
