great upgrade for old style 2-D flashlights, You know the ones everyone has sitting in the kitchen drawer with the dull or burned out bulb you forgot to replace. I put one of these in an 80\'s Duracell 2D flashlight and was amazed how much brighter it is than the PR blulb I took out. Next I put 1 in my 6 Volt handheld Lantern that the PR-13 bulbs never last now 2 6-Volt Lantern batteries should last for days during the summer power outages. $12 is a bargain for a Lantern that lasts for days