This instrument dial slides into one of your font tray dovetail and is locked in place by a single thumb screw. This is large and will only work on one of the larger format machines like you see in the pictures. This will not work on a model GM or a mini grav. There is a single notch at the 0° position to lock the wheel in place. It is up to the user to add additional notches if they desire to rotate this 90° or 180° etc. This will be wrapped up in cardboard and padding and shipped in a medium flat rate box for protection. If you pay by noon Eastern time I will mail your package the very same day. The engraving machine and the measuring instruments are not part of the sale.