According to the first aspect of the invention, syringe of the invention includes: cylinder, and plunger is movably disposed within the bucket and plunger rod, for driving the offer plunger. The syringe includes that first engagement member is arranged in plunger rod, when the engagement member includes surface, barrel is set to the first mesh piece with the grooved surface, so that the feedback given the user makes plunger rod relative to the mobile driving piston of cylinder with the second fastener. Wherein, plunger rod is advanced through with respect to cylinder to set a distance D, the first fastener moving distance D, wherein d ≥D.
