The X9 radiometer is a universally applicable measuring instrument for the determination of UVC irradiance at 254 nm with direct read-out in the units of µW/cm2. The meter is used together with the UV-3718 detector head to measure irradiance and dose in the UV-C spectral range at 254nm. Despite its compact dimensions, the meter offers a large display and an RS 232 interface. Operation is simple for the benefit of non-technical personnel.