The medical device having a retractable needle and a plunger movable seal

A medical device, the medical device having a barrel, a retractable needle, and a plunger assembly retracts the needle, the needle is retracted the cartridge assembly including a contact holding member and at least partially retracted before the holding member is held in inner tube, said plunger comprising a plunger seal having a body, the body with respect to at least one step fraction movable plunger rearwardly; said needle is retracted past the plunger comprises a plunger retraction inside the seal elastic net cavity, said holding member and said plunger seal are cooperating with the inner wall of the barrel to provide a seal of the liquid storage chamber in the interior of the device.