Inspired by early 20th century rotary knobs, the "Illuminator" adds vintage style to any room. A perfect compliment to our push button light switches, it's made of heavy-duty black resin and features a luminous mother-of-pearl inlay (the pearl does not actually light up). The raised lettering pays homage to Granville Woods, African-American pioneer of dimmer technology in the 1890s. This knob is designed specifically for use with Lutron brand rotary dimmers (available for purchase as a set - see items R-010FD-LMNTR-1 & R-010FD-LMNTR-3) . Measures 1 7/16" in diameter.