PURPOSE: To achieve a precise and easy assembly of slits by arranging a plurality of slits different in the width from each other lengthwise in one row to make an integral construction which is slid along the length common to these slits.

CONSTITUTION: A common blade 1 on one side of different kinds of slits have a straight edge line. Blades 2W6 opposed to the common blade of the slits are mounted on one base plate 7 facing the common blade 1 and arranged in one row along the length of the slits to construct five kinds of individual slits S1WS5 with the fixed width different from each other. A slider 8 is provided with projections P1WP5 at the position corresponding to the respective slits S1WS5 on one side thereof parallel along the length of the slits S1WS5 and one microswitch MS is fixed on the body frame 12. With the movement of the slider 8, the projections P1WP5 hit corresponding actuators of the switches MS to actuate.