Abstract: A new well bore centralizer construction; a well bore centralizer construction which may be shipped in disassembled condition by the manufacturer, occupying the smallest volume of space, to be later assembled; a field-assembleable casing centralizer consisting of a pair of vertically spaced apart collars and connecting, outwardly bowed leaf springs secured to the collars by a liner construction therewithin, wherein movement of the leaf spring ends in one direction is prevented by engagement therewith of liner tabs which engage openings in the leaf spring ends, movement of the leaf springs being prevented in the other direction by shaping of the collar and the positioning of the liner with respect thereto; improvements in the structure and methods of connection of the ends of leaf springs to centralizer collars in field assembleable centralizers.