The Miraco 677 Plunger is a replacement part specifically designed for Miraco's grey 521 high-pressure valves. It securely holds the valve plunger rubber (part 680) and comes with a plunger seat to ensure effective water flow regulation. Compatible with all Miraco automatic waterers using the grey valve, this plunger offers reliable water management and extends the life of your livestock watering system without the need to replace the entire valve.