Convenient to use: The battery voltage tester features a switch function button, allowing you to press and check battery capacity or real-time voltage, then turn it off. Includes an alarm feature; the battery meter display flashes when battery capacity is below 20 percent. Easy to read: Designed with a clear LCD digital display, the battery gauge indicator comes with a PVC waterproof screen protector and a bright backlight, enabling easy reading from various angles. Low power consumption, with a maximum of 5mA. For different batteries: The battery capacity indicator is compatible with 12V, 24V, 36V, 48V, 60V, 72V, and 84V lead acid batteries, ternary lithium batteries, polymer lithium-ion batteries, lithium-ion batteries (3-15 series), storage batteries, water batteries, and more. Note: Not suitable for lithium iron phosphate batteries, 1-2 series Li batteries, or more than 15 series Li batteries. Working voltage input: This package includes one battery tester with alarm, easy to use and replace in daily applications. Working voltage input range is DC 12V to 84V, capable of automatically detecting accurate voltage based on the connected battery. Widely applicable: The battery capacity voltage indicator can be used in various locations such as garden, home, or office. Reliable for long-term use, meeting diverse needs and enhancing convenience. Package includes: 2 pieces (battery not included)