American Lighting Dimmable LED S14 Opaque Light Bulbs, E26 Medium Base, Blue, 25-Pack Dimmable, LED replacement bulbs for indoor/outdoor light strings Professional grade LED lamps last 25,000 hours (6,250 days at 4-hours per day equals 17.1 years) Medium base, blue light bulbs S14 bulb shape, 120-volts, 1.4-watts 25-pack, medium base lamps, use with string light models: #LS-MS-24-48-BK or LS-M-24-48-BK