Casing structure of wrist exerciser

DETAILED DESCRIPTION An object of the present invention is to provide a separable casing structure of a wrist exerciser that allows a user to open the casing for replacing parts of the wrist exerciser.
Another object of the present invention is to provide a wrist exerciser having a separable casing to allow a user to replace malfunctioning parts for repairing/maintenance purposes.
To achieve the above objects, in accordance with the present invention, there is provided a wrist exercise comprising a casing defining an interior space rotatably receiving a rotor.
The casing includes upper and lower casing members.
The upper casing member has a first mating edge forming a first mating device.
The lower casing member has a second mating edge forming a second mating device for mating the first mating device to attach the lower casing member to the upper casing member whereby a circumferential groove is defined between the first and second mating edges.
A first retention ring is at least partially fit over the upper and lower casing members and forms an inwardly-projecting portion fit into the groove to securely retain the upper and lower casing members in position.