Temperature adjustable: USB micro-type cylinder heating rod for precise temperature control. The temperature can be set between 18-34°C, accurate to 0.1 degrees, providing the ideal temperature for fish. Compact design: As small as a thumb, it saves space and is suitable for mini fish tanks and micro-tanks with a water capacity of up to 4L. Heating element: Features a nickel soldering electric heating wire filled with sand for efficient heat distribution, ensuring high thermal conversion, rapid heating, and energy savings. Application: Specifically designed for small aquariums, this heater is space-saving and compatible with both freshwater and saltwater tanks. Quality tested: Designed with careful material selection and engineering to ensure reliable performance. Name: Aquarium Heater Specifications: 25W temperature control display, USB version Applicable scenarios: Fish tank, aquarium Note: Due to different production batches, there may be variations in printed labels and slight differences between the actual product and images, which do not affect normal use. Color: Black Material: Plastic + Metal Package Contents: 1 x Aquarium Heater (Other items not included) Note: Lighting and screen settings may cause slight color variations between the image and the actual item. Measurement error allowed within +/- 1-3cm.