ReptiZoo UVB Sensor Test Card (2-Pack)

This reusable card accurately measures ultraviolet (UV) radiation in just 10 seconds. Simply hold it within 5 cm of the basking lamp to check if UV light is being emitted. The card will display a purple color under the lamp when UV is present. Replace the bulb as needed, or sooner if no color appears. Each card can be used up to 500 times with 10-second checks.
Size: 5.4 × 8.5 cm (2.1" × 3.3")