Top Or Bottom Chassis Mount Ceramic Octal 8 Pin Cup Contact Tube Socket For EL34, 6L6GC, KT88, KT66, GZ34, 6SN7GT And Similar Octal Based Tubes. White glazed ceramic body. Just flip the clamp to change from top to bottom mount! Mounts to chassis with two machine screws, mounting centers approx. 1.50" or a bit more (mounting clamp is slotted...). Chassis bore hole required is around 1.060".