Practical designs: The battery capacity voltage indicators feature a switch function button, allowing you to press and check the battery capacity or real-time voltage, then turn off. Includes an alarm design that causes the display to flash when battery capacity drops below 20 percent. Compatible with various batteries: The battery gauge indicators work with 12V, 24V, 36V, 48V, 60V, 72V, and 84V lead acid batteries, ternary lithium batteries, polymer lithium-ion batteries, 3-series lithium-ion batteries, storage batteries, water batteries, and more. Note: Not compatible with lithium iron phosphate batteries, 1-2 Li batteries in series, or more than 15 Li batteries in series. LCD digital display: The battery capacity gauge includes a PVC waterproof screen protector with green backlight, enabling clear reading on the LCD display from multiple angles. Low power consumption, maximum 5 mA. Wide applications: These battery meters with alarms can be used in various settings such as gardens, homes, offices, and more. Durable construction ensures long-term service, meeting diverse needs and providing reliable performance. Package content: Includes 2 battery meters with alarm, suitable for convenient use and replacement. Working voltage input range is DC 12V to 84V, with automatic detection for accurate voltage readings based on the connected battery. Specifications: Working temperature: 040C Display: Capacity / Voltage Backlight: Green Product dimensions: 2.41 x 1.31 x 0.53 inches / 61.3 x 33.3 x 13.5 mm Mounting hole dimensions: 2.3 x 1.12 inches / 58.5 x 28.5 mm Color: Black Material: ABS Package Contents: 2 x Battery meter Note: Not compatible with lithium iron phosphate batteries, 12 Li batteries in series, or over 15 Li batteries in series. The package includes only the items listed above; other products are not included. Note: Lighting and monitor differences may cause slight color variations between the image and the actual item. Measurement error allowance is +/- 13 cm.