Temperature adjustable: USB micro-type cylinder heating rod for precise temperature control. The temperature can be set between 18°C and 34°C, accurate to 0.1°C, providing the ideal water temperature for fish. Compact design: Small size, approximately the size of a thumb, space-saving and suitable for mini fish tanks and micro-tanks with a water capacity up to 4L. Heating element: Features a nickel soldering electric heating wire filled with sand for even heat distribution, efficient energy conversion, fast heating, and energy savings. Application: Specifically designed for small aquariums, does not occupy tank space. Resistant to corrosion and suitable for both freshwater and saltwater environments. Quality tested: Undergoes rigorous testing from material selection to design to ensure reliable performance and durability. Product name: Aquarium Heater Specifications: 25W temperature control display, USB powered Applicable scenarios: Fish tank, aquarium Note: Label printing may vary slightly due to production batches. Minor differences between the image and actual product may occur, which does not affect normal use. Color: Black Material: Plastic and metal Package contents: 1 x Aquarium Heater (Other accessories not included) Note: Lighting and display differences may cause slight color variations between the image and the actual item. Measurement error allowed within +/- 1-3cm.