Hello Ebayers , up for buy it now is a pair of JAN 5751 preamp tubes G.E. merit matched tubes new in original boxes from G.E. ..JAN stands for Joint Army Navy , these were approved by the U.S. Government to be officially used for their military operations (and we all know what that takes to happen extensive testing and approvals .  These were approved to go to war to defend our country so they are surely good enough to work in your guitar amplifier perfectly.. We want to be clear you are potentially buying 2 tubes total .... When we say merit matched we are measuring the merit level of our SECO tube tester ..  It just shows us the merit levels are the same and can be used together effectively ..An example on our SECO tester if one tube measures 105 merit and another only 100 we wouldn't consider that a merit matched set , we usually consider within 1 point merit matched , even though both are over 100 merit which is amazing " like brand new " , we will make sure both tubes are over 100 and will lable them what the both measured when they arrive .  China and Russian made tubes usually don't make it to those levels of 100 or more .   We want to be clear that we don't have a matching tube device ,  but we have sold many tubes in this manner and have had great success with repeat Ebay and in store customers.  Just check our feedback on Ebay .  WITH BUY IT NOW YOU GET FREE ECONOMY SHIPPING!!!!!!!!