The TNF823 with Sentry 12-Key Controller is a round, top loading Insulating FireBrick Kiln with groove mounted Elements. It measures 16.5″dia x 22.25″D inside. The TNF823 Kiln is rated to 2350°F. It fires on 208 Volt / 1 Phase and is Direct Wired. Drop Down Switchbox. Rated to 7200 Watts.