Abstract: A Bluetooth earphone set, which includes a main unit that houses an auto-reversible first winding mechanism and an auto-reversible second winding mechanism, an earphone cable coupled to the auto-reversible first winding mechanism for voice output, a signal connector cable coupled to the auto-reversible second winding mechanism and connectable to a cell phone, a switch, which is switched between a first position for enabling the earphone cable to output voice signal that is received wirelessly from a cell phone by the main unit and a second position for enabling the earphone to output voice signal that is received from a cell phone through the signal connector cable.

Abstract: A low-noise transmitting receiving earset includes a housing covered with a grille, a speaker mounted inside the housing adjacent to the grille and facing the back side of the housing, a first microphone mounted in the hub of the grille and facing the front side of the housing for picking up resonant sound waves from the external auditory canal of the user's ear, and a second microphone mounted inside the housing remote from the speaker for receiving voices directly from the user's mouth.

Abstract: A safety hypodermic syringe formed of a barrel, a plunger, a retainer, a rubber stopper, a needle holder and a needle is disclosed. The retainer is forced by the plunger into engagement with the needle holder when the plunger is pushed forwards to squeeze a fluid medicine out of the barrel so that the needle holder and the needle are moved carried by the retainer into the inside of the barrel to have spring hooks of the retainer hooked on the rear end edge of the barrel upon a back stroke of the plunger and the needle holder with the needle are kept in the rear side inside the barrel as the plunger is pushed forwards again.

Abstract: A interference-free transmitting receiving earset includes a housing houses a speaker, a grille covering the speaker and having a front center tube, and two microphones mounted in the center tube of the grille in reversed directions to pick up sound waves from the user's external auditory canal and wound waves from the speaker respectively and to eliminate interference of sound waves from the speaker with sound waves produced by the user in the external auditory canal.

Abstract: A Bluetooth earphone set, which includes a main unit that houses an auto-reversible first winding mechanism and an auto-reversible second winding mechanism, an earphone cable coupled to the auto-reversible first winding mechanism for voice output, a signal connector cable coupled to the auto-reversible second winding mechanism and connectable to a cell phone, a switch, which is switched between a first position for enabling the earphone cable to output voice signal that is received wirelessly from a cell phone by the main unit and a second position for enabling the earphone to output voice signal that is received from a cell phone through the signal connector cable.

Abstract: A low-noise transmitting receiving earset includes a housing covered with a grille, a speaker mounted inside the housing adjacent to the grille and facing the back side of the housing, a first microphone mounted in the hub of the grille and facing the front side of the housing for picking up resonant sound waves from the external auditory canal of the user's ear, and a second microphone mounted inside the housing remote from the speaker for receiving voices directly from the user's mouth.

Abstract: A safety hypodermic syringe in which the plunger is breakable into a front part and a rear part after the service of the safety hypodermic syringe so that the front part can be kept with the needle assembly inside the barrel and the rear part can be inserted into the front side of the barrel and capped on the needle cannula of the needle assembly inside the barrel to prevent contamination.

Abstract: A safety hypodermic syringe in which the plunger is breakable into a front part and a rear part after the service of the safety hypodermic syringe so that the front part can be kept with the needle assembly inside the barrel and the rear part can be inserted into the front side of the barrel and capped on the needle cannula of the needle assembly inside the barrel to prevent contamination.

Abstract: A interference-free transmitting receiving earset includes a housing houses a speaker, a grille covering the speaker and having a front center tube, and two microphones mounted in the center tube of the grille in reversed directions to pick up sound waves from the user's external auditory canal and wound waves from the speaker respectively and to eliminate interference of sound waves from the speaker with sound waves produced by the user in the external auditory canal.

Abstract: A safety hypodermic syringe in which a pull handle is inserted into the plunger and adapted to pull the needle assembly backwards to the inside of the plunger in the barrel after the service of the safety hypodermic syringe. The pull handle has a middle neck through which the rear part of the pull handle can easily be separated from the front part of the pull handle by bending, enabling the separated rear part of the pull handle to be inserted into the plunger in the barrel and hooked up with the front part of the pull handle.