The TNF273 with Sentry 12-Key Controller is a round, top loading Insulating FireBrick Kiln with groove mounted Elements. It measures 28″dia x 22.25″D inside. The TNF273 Kiln is rated to 2350°F. It fires on 240 Volt / 1 Phase and is Direct Wired. Drop Down Switchbox. Rated to 12000 Watts.