OHD leads the industry as the only global provider of both OSHA- and ISO-recognized quantitative respirator fit testing technologies. With QuantiFit2™ and AeroFit®, we deliver not only precise results but also an intuitive, seamless user experience. OHD is also the U.S. Master Distributor for Gilian air sampling equipment. Beyond fit testing and air sampling, we provide a comprehensive suite of occupational health and safety products, including noise monitoring, spirometers, audiometers, and other advanced instrumentation, to empower safer workplaces. With a full-service calibration department and industry-leading technical support, OHD aims to be your partner for technical solutions.