Metallics SW77M Washers 5/8 Flat St-zn (Box 1000)

The SW77M is a 5/8 inch flat washer, so it pairs with 5/8 inch bolts, anchors, and threaded rod. For 5/8 inch all-thread hanging runs of strut, conduit trapeze, or equipment anchorage, this is the washer that goes under the nut.

Material is steel with a zinc finish. Zinc plating gives basic corrosion resistance for indoor and protected locations, mechanical rooms, and dry or damp interior runs. For direct weather exposure, submerged, or corrosive environments, step up to hot dip galvanized or stainless washers instead.

They ship as a box of 1000 pieces, a single bulk pack rather than a small hardware card. That quantity suits a contractor stocking a service truck or an MRO crib standardizing on 5/8 inch hardware across a facility.

Different jobs. A flat washer like the SW77M spreads the load of the nut over a wider area and protects the surface or strut from being dug into, which is what you want against sheet metal, strut channel, or wood. A split lock washer resists the nut backing off under vibration. On vibrating equipment it is common to use both, flat washer against the material and lock washer under the nut.

It is an ANSI dimensioned 5/8 flat washer, so the inside and outside diameters follow the standard pattern rather than a proprietary one. That matters when you are mixing it with fasteners already on the job.

Origin is listed as multiple countries, so individual boxes may come from more than one source. Buyers working to a domestic sourcing requirement should not spec this item for that purpose.