Tecnomagnete 550 Lb MaxX 250 Sheet Plate and Bar Lifting Magnet 12053

  For sale is a Tecnomagnete Co. MaxX 250 Plate, Sheet and Bar Lifting
  Magnet, Serial No.05202.  Plate lifting capacity: 550 pounds.  Bar
  lifting capacity: 220 Pounds.  Permanent type magnet with magnetize /
  release lever.  Area of base:  5-5/8" X 2-5/8".  Bolt-on, removable
  eye-hook. This magnet has an extra safety feature, whereby it would
  not "click" if it does not provide a full magnetic force, for
  example if you use it to hold a piece of rebar or something. But 
  it would click, hold viciously etc if you attach it to a 
  steel plate.

(Click on the thumbnail images to enlarge)