A pH meter, also called a sensor or tester, is a device used to measure the acidity or alkalinity of a substance. A pH meter has either a portable or a benchtop body. Many portable meters are handheld devices. Some testers have an internal sensor, and may have a tip and body that fit inside of a container for measurement. A meter is commonly used in many different environments from laboratories to field research and manufacturing facilities. Researchers, manufacturers, and hobbyists use a pH meter in aquaculture, agricultural, wine-making, and water-testing, and for scientific applications. Some pH meters may measure additional parameters such as dissolved oxygen (DO), conductivity (also called electro-conductivity or EC), temperature, total dissolved solids (TDS), salinity, resistivity, or oxygen reduction potential (ORP)/mV.Bibby Scientific manufactures laboratory equipment such as shakers, centrifuges, incubators, and water baths under the Stuart, Jenway, and Techne brand names. The company is headquartered in Stone, Staffordshire, UK.