Features stainless steel bolts and washers wing-nuts. Plug measures: 1 7/16 inches at top and 15/16 inch at bottom. Safely seal off in-ground plumbing lines during freezing conditions! Winter freeze plugs are used to plug your swimming pool pipes after they have been drained to prevent water from entering the pipes and causing freeze damage. Simply screw plugs into all return and drain inlets after blowing out lines. The extra long taper allows for a more secure fit. Extended bolt for plugging deeper into pipes.