Abstract: A writing instrument in the form of a ball pen has two cartridges capable of being alternately moved into the writing position by rotating the barrel. A provision is made for a space in the top part of the barrel for accommodating or receiving various accessory devices such as stamping mechanisms, marker pens or the like. The invention includes a guide tube housed within the barrel and having two longitudinal slots therein. Two slides having small tubes for receiving the writing cartridges, are movable back and forth on offset guide rails on the guide tube. The slides are forced into contact with a curve switching cam surface of a switching casing by springs. By rotating the switching casing, the one or other slide and thus the small tubes with the writing cartridges inserted therein are alternately pushed toward the bottom of the writing instrument and into the writing position.

Abstract: A writing utensil is provided, such as a ball-point pen having integral stamping equipment, which includes:a stamp and a stamp pad arranged on supports which are articulated by pivoting about axes perpendicular to the longitudinal axis of the writing utensil between positions approximately parallel to the longitudinal axis and positions approximately perpendicular to the longitudinal axis, anda removable cap which friction locks on the supports when the supports are in the position parallel to the longitudinal axis, so that the stamp rests disposed against the stamp pad.The support for the stamp pivots at its center point on an extension of the rear part of the writing utensil. The extension, rounded off on its outer side, extends to a length corresponding to one-half the length of the stamp support.