A hypodermic needle luer lock is a threaded connection on a syringe that creates a leak-free seal. Healthcare workers can attach needles, tubes and other equipment to the lock to perform a variety of activities related to patient care. hypodermic needle luer lock This accessory is standardized, and all medical supply companies manufacture and design to the same specifications. Standardization allows for the interchangeable use of various medical devices, enabling healthcare workers to choose the best device for a given task without worrying about compatibility.