Sylvania — one pair of 7591A tubes test strong — vintage One is older Sylvania with full dark base and pink writing One is Philips / Sylvania with faded light blue printing on the glass 4500 is “good” and Older tube tests 5000. Newer coin base tube tests 6000 Likely used to some extent If you purchase, you will get the 2 tubes shown in the photos Made in USA US and Canada buyers ONLY. Free shipping, via US Post Office Priority Mail. Will be packed *carefully* prior to free shipping! Check out my other tube listings… I have many old and unusual tubes