Temperature adjustable: USB micro-type cylinder heating rod for precise temperature control. The temperature can be set between 18C and 34C, 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-plated electric heating wire filled with sand for efficient heat distribution, ensuring high thermal energy conversion, fast heating, and energy savings. Application: Specifically designed for small aquariums, this heater does not occupy extra space and is compatible with both freshwater and saltwater tanks. Quality tested: Undergoes a rigorous selection process from material sourcing to product design to ensure reliability and performance. Product name: Aquarium Heater Specifications: 25W temperature control display, USB version Applicable scenarios: Fish tank, aquarium Note: Due to different production batches, label printing may vary. Minor differences between the image and the physical product may occur, but these do not affect normal use. Color: Black Material: Plastic + Metal Package Contents: 1 x Aquarium Heater (Other items not included) Note: Lighting and monitor settings may cause slight color variations between the image and the actual item. Measurement error allowance: +/- 1-3 cm.