These interesting-looking bulbs are LED's, and they're also spotlights. Instead of having light go everywhere inside the base, these bad boys direct the light straight up and out. More importantly, LED's = No Heat, an important consideration when building a sealed wood box. These particular LED bulbs were pretty reasonable, around $10 apiece and they fit standard E27 light bulb sockets. But I've seen other LED bulbs that are extremely expensive...