Hickok 1575B / RD1575 Mutual Conductance Tube Tester
Please read the calibration report and the last page includes the upgrades done and other important information.
All the meters are accurate.  New film and electrolytic capacitors and protection diodes for the meter.
See pictures 6 thru 11 for calibration specs and information that includes the added bias and plate current jacks for this 1575. These pages should tell you all you need to know about this 1539B which is the the RD-1575. Exactly the same except this one was labeled for the military.
You will see in pictures 12 and 13 a 6AU6 being tested using the self-bias option.
The multimeters seen in the pictures are not included and shown for demonstration only!
 
Please see the calibration information in the pictures.
 
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Please contact in advance of purchase for shipping costs internationally. The cost for shipping in the USA will be deducted from the total cost of shipping when shipped internationally.
 
Here is what AI came up with: 
The Hickok 1575B RD1575 Tube Tester is a high-quality vintage piece of equipment that has been expertly upgraded to work like new. This tester is designed to accurately test and measure the performance of vacuum tubes, and features self-bias and plate current, as well as bias jacks for precise results. This is an essential tool for serious electronics hobbyists and professionals alike. Get the most out of your vacuum tubes with the Hickok 1575B RD1575 Tube Tester.