Abstract: A retractable marking pen having a tip guard to protect the writing tip (nib) from contact with external material when the ink cartridge to which the tip is connected is retracted into the pen casing. The tip guard is composed of a pair of guard flaps which open allowing the writing tip to pass therethrough when the pen is placed in writing mode and close over the tip when the pen is in retracted mode. The guard flaps are a pair of continuous panels which extend from the inside wall of the pen casing and are integrally molded with the casing. Each guard flap has a rear section which is essentially parallel to the pen casing wall surface and a forward section which slopes towards the axis of symmetry of the pen casing at the writing end of the pen. A major bend line in the surface of each flap separates the forward section from the rear section of the flap and forms an abutment wall.

Abstract: A multicuvette rotor assembly for use in a clinical chemistry analyzer of the centrifugal type includes a body member that defines a circumferential array of spaced radially extending recesses, with a divider member in each recess to define a first chamber and a second chamber radial outward from said first chamber; and a ring member that has a mating reference surface seated on an annular reference surface of the body member, with the inner peripheral surface of the ring member located outwardly of the middle of the second chambers.