What does the magnet and how it work?

What does the magnet and how it work?
"nodes": [
["id", "posX", "posY", "posZ"],
{"collision":true}
{"frictionCoef":0.5},
{"selfCollision":true}
//--TOW HITCH--
{"nodeMaterial":"|NM_METAL"},
{"group":"pickup_towhitch"}
{"nodeWeight":5},
["tw", 0.0, 2.76, 0.58,{"magnet":"true"}],
["tw2", 0.0, 2.76, 0.49,{"magnet":"true"}],
{"group":""}
],
i didn't found anything about this on forum.

 

Thanks, but sounds good anyway
Waiting for the good things in the future.