The Additel ADT959A is a high-accuracy, handheld digital pressure calibrator with a wide pressure range of -14.5 to 3000 psi (-1 to 200 bar). It features a built-in pressure sensor with an accuracy of 0.025% of reading, and a resolution of 0.001 psi (0.0001 bar). The ADT959A also includes a built-in 24-bit A/D converter, which provides high-resolution measurements. The calibrator is powered by a rechargeable lithium-ion battery, and it has a long battery life of up to 20 hours. The ADT959A is a versatile and portable pressure calibrator that is ideal for a wide range of applications, including pressure gauge calibration, pressure switch testing, and leak testing.