Repair and test kits have a variety of applications, and are usually used by technicians servicing the HVAC/R systems, however with some amount of knowledge and understanding of how this structure works - anyone is able to use this kits to analyze the system and identify the problem. Besides the above mentioned instruments there is a variety of devices like thermometers, filters, various liquid injectors, replacement parts, refrigerant identifiers etc. These instruments are usually grouped in kits and sets according to their intended use and system that they are applied to. These kits may vary depending on service application and on the price. Some kits have simple sets of hand tools needed to adjust and open outer coverings and connections, while others have pricy instruments like leak detectors and some types of meters.