Abstract: In a syringe, in which a needle assembly is engaged by a plunger and withdrawn into a syringe barrel for safe disposal, the plunger slides in a resilient insert secured at the proximal end of the barrel. The insert engages an annular ridge near the distal end of the plunger when the plunger, with the needle assembly attached to it, is fully withdrawn, thereby securely locking the plunger to the barrel, and reliably preventing distal movement of the plunger after the needle assembly is withdrawn into the interior of the barrel. The part of the plunger that protrudes proximally from the barrel may then be snapped off.

Abstract: A watch case is arranged with a periphery having a lobe and a recess to cooperate with the human anatomy and ergonomics. A specially shaped watch case provides a means to couple a wristwatch to a wrist bone. The coupling provides mechanism to reduce movement of the watch about the wrist and to locate an optical probe with respect to a preferred region of tissue. In addition to the special shape of the watch case, an arrangement of watch bands and their attachment to watch cases advances the objectives of devices of the invention.