Makita 231984-3 — genuine Makita ring spring (d=25 mm) engineered to restore factory tension and retention in the hammer/coupling assembly of compatible Makita rotary and demolition hammers. Durable metal construction resists fatigue under repeated impact, keeping the barrel/muff coupling seated tightly to reduce play and maintain smooth hammer action. Fits select Makita models (examples: HR5001C, HR4001C, HM001G, HM1202C and similar models) and is the exact part specified by Makita for those assemblies. Replace a worn or broken 231984-3 to return reliable percussion performance and extend the service life of your original Makita tool.