The Techno Tools Corp. D400 Leak Detector features a long-life solid electrolyte sensor designed to detect all HCFC, HFC, HFO, and HC refrigerants. The instrument is certified to comply with SAE Standards J2791 and J2913 as well as Euro Standard EN14624. The instrument does not require rechargeable batteries. The D400 offers automatic calibration and reset to ambient levels, with three adjustable senstivity levels. The D400 uses 4 AA alkaline batteries, and has a low battery indicator.