LED Mini Bulb Size: Approximately 35mm long x 11mm in diameter, with a hole for string You can switch it ON/OFF by twisting the cap, and easily light up balloons, lanterns, paper lanterns, etc. It has a lifespan of about a week, using it for 2-3 hours a day, but the light output will gradually decrease over time. The built-in button battery (LR41) can be replaced, allowing for reuse. (3 button batteries) 【Caution】Please wrap used batteries individually with insulating tape such as cellophane tape to prevent them from touching other batteries or metal objects. The above is an excerpt from the manufacturer's website. We are not the manufacturer, so we cannot answer detailed questions, please understand. 2 for 450 yen, 3 for 600 yen