Check the listing for details. LUMAPRO 21U553 18.76 W,S8,BA15d 21U553. Condition: New. Listed at 2.40 USD. Incandescent Bulb, Bulb Base Type Double Contact Bayonet (BA15d), Bulb Housing Glass, Bulb Shape S8, Bulb Finish Clear, Color Rendering Index Not Applicable, Color Temperature 2750K, Lumens 264 lm, Light Technology Incandescent, Shatter-Resistant No, Trade Number 308, Voltage 28V AC, Watts 18.76 W, Bulb Beam Angle Not Applicable, Rated Life 300 hr, Dimmable No, For Enclosed Fixtures No, Three-Way No, Light Color White, Rough Service No, Indoor/Outdoor Usage Indoor Only, Overall Length 2 in These S-shaped miniature light bulbs have a double-contact (DC) bayonet base, sometimes known as a BA15d base. There are two contacts on the bottom of the base. The base has lugs on either side that lock the bulb in place when the bulb is pushed into a compatible socket and twisted.S-shaped miniature lig.