These used tubes have been tested on a calibrated Hickok 752 or 752A. All tubes are tested for transconductance, internal shorts, defective elements and gas leakage. Based on initial appearnce and overall condition I believe these are used tubes, however their respective test results indicate that they may be used again with full confidence. All tubes are tested with approximately 150 VDC plate voltage, or the otherwise recommended voltages. Specialty tubes are tested according to manufacturers specifications. Tested and proven values of transconductance are written on the box in which the tube is sold and shipped. All tubes must exceed minimum Gm values by at least fifteen percent to even be considered for remarketing and sale. Most tubes exceed minimum values by a much wider margin. Tubes that still have an original box in acceptable condition are sold in that box, all others are repackaged. All tubes have been cleaned, pins straightened, wrapped in an internal paper cushion and boxed in new plain, white boxes. If shipping seems too high, please request an invoice prior to payment. My inventory is updated and replenished about once a month. To fill orders I will always select the best tubes from the available and/or remaining stock on hand. I will combine orders of multiple tubes to save you as much shipping costs as is possible, this applies only to tubes purchased and paid for on the same day. Listed price is for a single tube. All tubes are sold with a money back guarantee. Domestic sales: All domestic orders are subject to a minimum shipping charge of $7.00. Please add 50 cents for each additional tube. (Please don't order one three dollar tube and then be upset because it cost seven dollars to ship it to you. I am telling you the cost up front so there are no surprises.) International sales: Shipping for international orders is higher than for domestic orders, please expect costs to be a bit more. I do charge a $5.00 handling fee for international orders, as these orders must be packaged with extra padding and wrapping to ensure they arrive to you unbroken. (International handling fee does not apply to Canada.) International orders valued at $50.00 USD or higher must be sent by a method that provides package tracking, this costs more, please be aware of it. I will not sell to Italy, Chile or Brazil without special arrangements, I have had too many packages "lost" in these countries. I do not sell any defective or weak tubes. These tubes are crushed, and removed entirely from the product stream. It is my desire to be the source you turn to first for all of your vacuum tube needs, I want your business today and I want it tomorrow. If you have a specific tube you are looking for, but don't find it listed here, please feel free to contact me via the E-bay mail system. I have thousands of tested tubes that are slow movers and thus not listed. Arrangements can almost always be made within the system. Thank you so much for looking over my products, and I look forward to doing business with you. Please sign up for my online newsletter. Randy Withers