https://overhoff.com/product/model-321nppm/
Model 321NPPM | Overhoff Technology Corporation
Single-range nuclear power plant monitor, includes noble gas compensation, plate-out proof ion chambers, industrial NEMA-12 enclosure, and other features...
overhoff technologymodelcorporation
https://overhoff.com/product/model-311-hmi/
Model 311-HMI | Overhoff Technology Corporation
Single range, single ionization chamber
overhoff technologymodelhmicorporation