Restore the original sound of your older Mesa Boogie amp. These are the real thing, exactly what is called for in those amps. They are very sturdy construction and have a nice rich tone with lots of booming lows and singing highs. These are not the currently available tubes sold by Mesa Dealers. We are not affiliated with Mesa and do not represent them in any way.The quads are tightly matched using a Maxi Matcher 2 after being tested on a TV7/D and a Roetest Professional Computer Tube Testing system.