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Electric lifting magnet used on excavator or crane, for sorting out steel scraps, is also referred as excavator magnet, or scrap magnet, scrap handling magnet, scrap yard magnet, junkyard magnet. They could be round, circular or rectangular.
link:https://www.kinocranes.sg/overhead-crane/5-ton-lifting-magnet.html
5 ton Lifting Magnet | Kenancranes