These Patent pending ball bearing swivels are encased and sealed in solid copper. I have designed, and manufacture them myself and use them in my heavier sculptures. Ball bearing assembly provides for nearly frictionless action that allows kinetic sculptures to spin with ease. These swivels will out preform any swivels that are typically meant for fishing and they can not pull apart. I offer this product seperately for other artists that are looking for an affordable super heavy duty swivel. Other applications include pet runs, large bird teathering, stunt kite flying, Large game fish, swingsets, etc. Larger swivel has been tested to over 400lbs. Recomended max. load is 200lbs. Support loop is brazed not soldered to the unit for maximum strength. Recommended Max. load for the smaller swivel is 50.00 lbs.