The 4353375, also known as the Fluke-721Ex-3650, is an intrinsically safe dual-sensor pressure calibrator designed for high-accuracy measurements in applications like gas custody transfer. It features two isolated, stainless steel pressure sensors: a low-pressure sensor covering -14 to 36 psi with 0.035% full-scale accuracy, and a high-pressure sensor for 0 to 5000 psi with 0.025% full-scale accuracy. The device can also measure 4 to 20 mA signals and temperature with an optional Pt100 RTD probe. Its large backlit display can show up to three inputs at once. Certified with ATEX and IECEx for use in Zone 1 hazardous areas, this calibrator is an ideal tool for gas flow calibration and other critical processes in potentially explosive atmospheres.