TestedNew Old Stock / New in BoxGm 4100Minimum Gm 2700Gray Plates, Halo “O” GetterDate Code 67-36 TAll tubes are tested using my Amplitrex AT1000 (Fixed Bias) or Calibrated Western Electric KS-15750-L2 (Similar to Hickok 539B) or my Hickok 539CNew items added every week, so check back often! Shipping insurance is offered and is highly recommended! I always combine Shipping when PossibleInternational bidders please e-mail me for shipping & handling quotes if not otherwise listed in Ad drop-down box. Your items will be shipped promptly after your payment is confirmed. Payment is due within 7-days of sale! Please e-mail me with any questions! Track Page Views With Auctiva’s Counter