COUNTING GAS: P-10 (10% methane, 90% argon is recommended.  Other counting gases are also acceptable.
OPERATING VOLTAGE:
Typically 1100-1400 volts (alpha)
Typically 1500-1800 volts (beta)
COUNTER THRESHOLD SETTING: Typically 3-4 mV
BACKGROUND:
Alpha - typically less than 10 cpm
Beta - typically less than 250 cpm
EFFICIENCY (4 pi geometry):

3-7% Tc-99

SIZE: 1 1/2" (3.75 cm) OD. 9.5" (24.13 cm) overall length (not including fittings), 6" (15.24 cm) active length
GAS CONNECTORS: fittings for 1/8" hose
SIGNAL CONNECTOR: BNC