Sheriff's departments need highly trained officers to respond to emergency or violent situations in the jail system. Instead of relying on rank-and-file officers, who may not be trained in specialized operations such as cell extractions, violent prisoner transport, etc., many sheriff's departments have developed their own SERT to deal with many situations that require the specialized use of teams trained to deal with dangerous and potentially violent situations. Many SERT's have expanded the expertise of their members to prepare them to respond to emergencies outside of the jail system as well. The Henry County Sheriff's Office (Illinois), for example, has 14 technicians trained to deal with emergencies that involve hazardous materials. The Johnson County Sheriff's Office (Kansas) uses its SERT to execute high-risk arrests as well as conduct operations within the jail system. Training for SERT members is intensive. The Fairfax County Sheriff's Office (Virginia), for example, requires each SERT candidate to complete a basic 50-hour certification school, which is operated by the county. Those who complete the school have a 1-year probationary period, after which they are accepted as a full member of the team. Typically, the members of a SERT are officers with various duties in the department who are on call 24 hours to fulfill their responsibilities as SERT members as the need arises.