Mechanism for varying the finger grip area of a writing implement

A writing implement having an outer casing, a substantially cylindrical main body portion, means carried within said body portion for producing legible markings and having a writing tip exposed at one end of said body portion, said body portion having an area of reduced diameter to accommodate thereon a finger grip section, said finger grip section comprising a plurality of compressible "O"-ring members axially aligned along said main body portion, a plurality of annularly shaped spacer elements carried on said main body portion and located between adjacent "O"-ring members, said spacer elements having an inside diameter approximately equal to the outside diameter of said reduced diameter area of said body portion so as to be supported thereon and having a flange and curved transition surfaces between said flange and the major surface of said element on both sides thereof, thus forming a contoured cross-sectional shape, said transition surface having a radius of curvature approximately equal to the cross-sectional radius of said "O"-rings forming a supporting socket therefore which has a shape complementary with the circumferential shape of adjacent "O"-ring members to provide support therefore, first and second abutment members carried on said body section and located on opposite sides of said finger grip section, one of said abutment members being axially movable toward and away from the other abutment member to effect compression of said "O"-ring members when said movable abutment member is moved toward the other abutment member so that the radial distance between said body section and the circumference of said "O"-ring members is increased when said abutment member is moved in one direction and decreased when said abutment member is moved in the other direction, thus varying the diameter of said finger grip section.