A Retro Style C9 Christmas Bulb is the largest of the C Style Light Designation. The Bulb is 1 Inch in Diameter and can be seen from far distances. We carry C9 Lights in numerous Shades, with Transparent and Opaque Style Bulbs in our Selection. Our Lights are UL Listed for both Indoor and Outdoor use and many of them are Commercial Grade. We also have Retro Glass, Ceramic & LED options available.