Miniature Geiger tube type SBM-10 made for detecting beta and gamma radiation. It is designed to operate between 370 to 480VDC (perfect for use with our C8600ASB unit). It has a plateau length of 100V, slope of 0.125%/1V, working range of 0.04-400mKR/S, cobalt-60 pulse sensitivity 12 pulse/mKR, and dead time 64mKS. Size is 26mm (L) x 6mm dia., small center lead is (+). This tube is new old stock made in Russia during the cold war. Every tube is tested for operation before we ship!