Measuring Pulls

"Pull" usually refers to a decorative hardware piece that has two holes. 

"Overall" is the length of the pull measured end to end.

"Center to Center" is the distance between the mounting screw holes on a pull.

"Projection" is the distance from the base to the topmost portion of the pull. 

"Clearance" the distance from the base of the pull to the nearest surface. 

"Diameter" refers to the thickness of the material used to manufacture the item 
made from round bar stock.

Measuring Knobs

"Knob" usually refers to a decorative hardware piece that has one hole.