2 Bare flashing bulbs to make your lights flash. these bulbs are 2.5 Volt .425 Watt replacement Mini Bulb Indoor/outdoor Christmas tree flasher lights. Commonly used on 100 and 150 light strands, smaller strands usually use a higher voltage bulb. These will only work if you get the correct voltage and wattage. You can put these bulbs in your bases to make your light strand flash as long as the voltage and wattage is the same and your string uses the standard style of mini bulbs. I also have other colors and styles of mini bulbs listed.