A medical syringe has a tubular body extending along an axis and having a front end and a rear end, a plunger axially slidable in the body and carrying a stem projecting axially rearward out of the body from the plunger, and a free piston slidable in the body forward of the plunger and subdividing the...http://www.google.es/patents/US6419656?utm_source=gb-gplus-sharePatente US6419656 - Medical syringe with braked step-advance plunger
