Foodie Puppies Round Thermometer for Aquarium Fish Tank Thermometer Sticker Round Aquarium Temperature Sticker Aquarium Thermometer Sticker Easy Read Fish Tank Thermometer Sticker 5Pcs/Set Aquarium Fish Tank Round Adhesive. 

Features:

• Measurement range: 18°C-34 °C Error: +- 1°C
• Using the environment: 18°C -34°C
• Self-adhesive design

Benefits:

• A betta thermometer helps maintain optimal health.
• It provides reliable functionality without requiring a significant investment.