As a genuine OEM York part

these units generally follow standard sizing

technicians should retain original hardware or utilize standard HVAC sheet metal screws for secure attachment to the housing

Replacing the gasket during annual inspections or whenever the head is removed prevents dangerous leaks and ensures the low water cut-off maintains precise calibration

and 5-blade propellers

McDonnell & Miller 336101 Paddle Kit As a genuine OEM YorkThe McDonnell & Miller 336101 Paddle Kit is a critical replacement component for maintaining accurate liquid flow switch operation in hydronic and industrial piping systems. This reinforced stainless steel paddle kit includes a 1 inch and a 6 inch paddle, specifically engineered for compatibility with the FS4 3RP and FS4 15RP models, as well as the FS8 W series. Designed for field technicians, these paddles are constructed from high grade 304