Japanese Organ brand machine needles for overlock/serger and coverstitch machines using the Elx 705 needle system. These needles differ from domestic machine needles in that they have a reinforced blade to reduce the occurrence of breaking and damage and both the front and back of the needle are grooved. Chrome plating reduces resistance. Not all overlock/serger machines require this type of needle. Check your user manual. Those listing 130/705 require a regular machine needle.