Assuming you are asking about a microscope (your question is very unclear on the subject), then the body or barrel of the microscope would do this, it would also be the point at which focus movement would be achieved.
Tube
The draw tube and the body tube connect the eyepiece to the revolving nose-piece.
The draw tube and the body tube connect the eyepiece to the revolving nose-piece.
The draw tube and the body tube connect the eyepiece to the revolving nose-piece.
The draw tube and the body tube connect the eyepiece to the revolving nose-piece.
The draw tube and the body tube connect the eyepiece to the revolving nose-piece.
The draw tube and the body tube connect the eyepiece to the revolving nose-piece.
The draw tube and the body tube connect the eyepiece to the revolving nose-piece.
The draw tube and the body tube connect the eyepiece to the revolving nose-piece.
Tube
The draw tube and the body tube connect the eyepiece to the revolving nose-piece.
The draw tube and the body tube connect the eyepiece to the revolving nose-piece.
The draw tube and the body tube connect the eyepiece to the revolving nose-piece.
The draw tube and the body tube connect the eyepiece to the revolving nose-piece.
The draw tube and the body tube connect the eyepiece to the revolving nose-piece.
The draw tube and the body tube connect the eyepiece to the revolving nose-piece.
The draw tube and the body tube connect the eyepiece to the revolving nose-piece.