Features: 🚀 - Simple Storage：Comes with 2-Packs UV sensor testing card and a card sleeve for easy carrying and storage. 🙈 - Easy to Test：Just place the testing card 3.5 inches away from the heating lamp and wait for 10 seconds, which can quickly test if there is an ultraviolet ray. 🌞 - Cover Testing：Cover the test card with your thumb，when the shows color difference between the thumb-covered and non-covered areas on the testing card, means that the UVB bulb is working normally. ⏰ - Recyclable Times：Compatible with sunglass test & sterilizing，reusable 500 times. When not in use, you need to put it in a card sleeve or store it in a dark place. 💡 - Campatibility：3.0 ~10.0 UVB bulb and Fluorescent bulb, such heating bulbs that carry ultraviolet rays. Package Included: UV Testing Card X2 Card Sleeve X2