Abstract: A writing unit locking mechanism in a writing implement having a mechanical pencil unit and a ball point pen unit both housed in a single holder cylinder. The locking mechanism has a writing unit selection member having a shift member shiftable under gravitational force to select one or the other writing unit and operated manually to actuate a chuck in the pencil unit and a catch shoulder provided on a unit cylinder of the pencil unit and adapted to engage directly with the holder cylinder or with an engagement member resiliently supported on the holder cylinder thereby to lock the pencil unit in its writing position. The pencil unit is released from its locked state simultaneously with the release of the selection member.

Abstract: A dual refill containing variable refill positioning writing instruments utilizing cam followers attached to two refill members and oppositely threaded spiral cam grooves within which said cam followers ride. The writing instrument includes an inner tubular shell having two spiral cam grooves each located substantially about one-half of the circumference of said shell and longitudinally displaced from each other and an outer tubular shell having two spiral cam grooves located around substantially one-half the circumference of the shell and longitudinally spaced from each other with each of the cam grooves corresponding with but oppositely threaded in respect to the inner shell spiral cam grooves. The inner shell nests within and is rotatable with respect to the outer shell.

Abstract: An exterior actuator structure for the cartridge retracting mechanism of ball-point pens and other writing instruments which use either an axially movable actuator button or a longer actuator cap, the exterior actuator structure having cooperating guide portions on the shell and on the actuator member defining axially extending guide teeth and cooperating guide slots or guide grooves, for a continuous shoulder-free exterior outline of the writing instrument. Extended guide grooves accommodate a clip.

Abstract: A writing instrument having a plurality of writing media assemblies separately positionable in writing position by a single independent actuator.