Nozzle getting clogged is a common issue after long run printing especially the nozzle size below 0.5mm. So this non-breakable stainless steel needle is specially designed for clearing the nozzle 0.4mm blockage without detaching the nozzle at all. Make sure the hotend is heated up before insert this needle.
If your nozzle clogging issue still exists frequently after several clearing processes, a new nozzle replacement is needed.