US Patent 7191492 Swivel structure having direction indication

A swivel structure having direction indication is described. The swivel structure includes a first swivel base and a second swivel base. The first swivel base has at least a window and the second swivel base has at least a first direction indication mark and at least a second direction indication mark. The first swivel base and the second swivel base have a first fixed position state and a second fixed position state. The first fixed position state and the second fixed position state switch to each other by swiveling. When in the first fixed position state, the first direction indication marks are shown through the windows and indicate the direction toward the second fixed position state. When in the second fixed position state, the second direction indication marks are shown through the windows and indicate the direction toward the first fixed position state.