One order equals 10 pieces. It comes with a heat sink, making it ideal for long-lasting illumination. Size: 31mm. The second photo is the original bulb, and the third is a reference photo. *For 12V vehicles. Depending on the vehicle model and installation location, the LED may be damaged by a momentary inrush current, so please take surge protection measures in this case. *There is polarity, so if it does not light up, try inserting it in the wrong direction. (Continuing to apply voltage while it is in the wrong direction will damage the LED.) *We cannot confirm or advise on compatibility regarding installation. *Damage due to the above reasons is not covered by warranty, so please have a professional install it.