Generally defined as an enclosed or partially enclosed environment, with or without restricted access, not designed for the stay of persons. They generally offer limited freedom of movement, limited accessibility and limited escape routes. Confined spaces are generally poorly ventilated and are susceptible to the accumulation of toxic, flammable, asphyxiant or otherwise hazardous compounds. Laws, regulations and best practices demand the confined space to be tested for various hazards before persons may enter, sometimes under the condition of further personal protection equipment. Gas detectors, often fitted with a pump, probe, a length of hose and ball floats, are used to check confined spaces for the presence of oxygen, combustibles and toxic compounds. Also, when working in a confined space, gas detection equipment is used to alarm workers of deteriorating conditions.