Abstract: A guard sensor device (100) is disclosed for use with a cable, pipe or wire transit (1) of a type that has one or more compressible transit elements (20) for allowing a sealed installation of one or more cables (2), pipes or wires, the sealed installation requiring appropriate mounting and tightening of one or more tightening members (41). The guard sensor device (100) comprises a base part (110; 210) and a cover part (120). The cover part is mountable onto the base part by means of a mechanical connection (114a-b, 124a-b), such as a snap lock connection, thereby forming between them an internal cavity (116a-b, 126a-b) for housing a protruding part of one (41a) of the tightening members (41) when being appropriately mounted and tightened. The guard sensor device (100) further comprises a sensor (130) disposed in either of the base and cover parts (110, 120).