Helium Handheld Detectors HT Products offer a variety of handheld leak detectors for many applications Helium MSLD Leak Detectors: Portable Trolley Mounted Large Vessels Sniffer Mode Detectors for Other Test Methods Portable / Hand-Held Trace Gas Detectors: Helium Refrigerant Hydrogen (5%H2 / 95% N2) Flammable / Combustible Gases