an assembly for connecting needles and catheters in i . v . applications , chemical analysis , etc ., includes a leak proof , sterile , self - sealing septum from which the needle is inserted . when the needle is retracted from the septum , the septum will reseal and thus maintain a leak - proof , sterile seal . the assembly is therefore reuseable , and this represents a considerable cost saving for patients who require continuous therapy such as with diabetics , cancer patients , and the like . the assembly includes a distal end having an outlet bore through which a catheter is inserted . the proximal end of the assembly is connected to an external adaptor to which is attached a needle . the septum is positioned between the distal end and the proximal end to provide a self - sealing seal between the needle and the catheter . this external adaptor with needle may be part of a syringe or shaped to accommodate any standard connector such as a luer lock . depending on the application , the fittings may be manufactured from a wide range of materials including plastics and metal . for example , as an inexpensive disposable item , the fitting would preferably be manufactured from molded plastic .