The present invention provides a mechanical seal device, capable of sealing special fluid such as chemicals, easy to be mounted to a device and small in size. The system includes an apparatus having a rotating assembly and a trackable body or plurality of trackable bodies, to mark a location of a preselected portion of the rotating assembly. Y is hydrogen or a protective group, such as tosyl. The compressive stresses applied by the combination of the prestressed shell and the pressure medium are additive and effectively preload the rails and the composite bore structure to resist overall forces encountered during projectile firing which, in a rail gun, include asymmetric loads upon the rails from electromagnetic repulsion forces and also axisymmetric bursting forces. The second handling subassembly has a structure same as the first handling subassembly except that the guiding rod of the second handling subassembly has a length greater than that of the first guiding rod.