Top or bottom chassis mount ceramic octal 8 pin tube socket/s for EL34, 6L6GC, KT88, KT66, GZ34, 6SN7GT and similar octal based tubes. White glazed ceramic body. Just flip the saddle to change from top to bottom mount. Please note that the saddle does not sit completely flat on the top surface of the chassis; there is a small gap because the portion of the ceramic body that contacts the chassis is thicker than the height of the metal saddle. This has not been an issue for most of our customers because most of 'em are 'bottom mounting' the sockets from inside the chassis. Mounts to chassis with two machine screws, mounting centers approx. 1.50" or a bit more or less (the saddle mounting holes are slotted...). Chassis bore hole required is around 1.055". Round portion of saddle 1.430", 1.817" at the ends.