The detent structure include 2 forms: Spring centred spool & without spring centred spool. Spring centred spool have those several structures: Detent in A Detent in B Detent in A & B Detent in A,B and O Without Spring return structure, it only provides AOB positioning function. We are manufacturer of various types of Hydraulic valves, such as: Hydraulic Section Valve, Hydraulic Reversing Valve, Hydraulic Control Valve, Hydraulic Floating Valve, Flow Divider Valve, Hydraulic Distributor, Hydraulic Rotary Valve and so on.