Many devices have been constructed and used to examine various parameters of thermal oxidation stability. Tools for defining fuel quality for specification purposes have been discussed in Chapter II, and simulators and large-scale devices have been described in Chapter III. The devices dealt with in this chapter have been used in many extensive research programs. Although the distinction is somewhat arbitrary, the devices described in this chapter are generally less complicated and smaller than those presented in Chapter III. In consequence, it has been possible to conduct research programs requiring extensive changes in experimental conditions with modest amounts of fuel and within reasonable time frames.