The DOB-50 GM tube was designed in East Germany for production and use in Poland during the peak period of the Cold War, around 1970. It has only become available recently when the Polish military began selling off surplus stocks of the tubes to make room for more modern equipment. The DOB-50 is sensitive to both Gamma and Beta radiation and generally operates at 400v, with peak voltage not to exceed 500v. It measures around 70mm/2.75” in length and 10mm/0.375” in diameter. As a testament to German engineering and superior Polish craftsmanship, each tube is hand-inscribed with its own serial number, verifying that it has met all Mil specifications and is certified for use in military equipment. Lifetime usage is estimated to be about 1 x 10(9) (10 billion counts/950 years with continuous average background of 2 CPM)