1. Each retentive arm should be opposed by a reciprocal component capable of resisting any orthodontic pressure exerted by the retentive arm 
2. Functions of reciprocal arm 4m*
   1. It provides stabilization/reciprocation against the action of the retentive arm.
   2. It also stabilizes the denture against horizontal movements.
   3. The reciprocal arm may act as an indirect retainer to a certain extent, i.e. when it rests on a supra-bulge surface of an abutment tooth lying anterior to the fulcrum line.
3. Design specifications for a reciprocal arm 
   1. It is positioned on the side of the tooth opposite to the retentive arm. 
   2. The reciprocal arm must be rigid and should not be tapered. 
   3. It is positioned on a tooth surface that is reasonably parallel to the denture’s path of insertion and withdrawal.
   4. It is ideally located at the junction of the gingival and middle third of the abutment tooth. 

Some special reciprocal elements 

1. At times, linguoplate can be used to provide reciprocation.
2. Sometimes, an occlusal rest positioned on the opposite side of the tooth will provide reciprocation.