Premium quality upgrade ceramic top or bottom mount 8 pin octal chassis mount tube socket for use with many popular tubes such as 6L6, 6V6, EL34, 6550, KT66, KT77, KT88, 5U4, 5Y3, GZ34, 6SN7, 6J5, 6SL7, and many more. Great replacement or upgrade for many newer amplifiers such as Marshalls, Fenders, and others. 1 1/6" chassis hole, Mounting centers are at 1 7/16"