This is 5mm Round Purple UV LED Diode Super Bright Water Clear LED Light which can be used to emit ultraviolet light.

Specifications Of UV LED:

1. Illumination Color: UV
2. Lens Color/Style: Water Clear
3. LED Size: 5mm
4. Lens Shape: Round
5. Forward Voltage: 3.4 - 3.6 V
6. Forward Current: 20mA
7. Maximum Operating Temperature: + 100 C
8. Minimum Operating Temperature: - 20 C
9. Peak Emission Wavelength λp --- 395 
10. Dominant Wavelength λd --- 425