As the name indicates it consist of magnetic catch and a holding plate. They are so fitted separately, that when the door opens or closes as the case may be, they come into contact with each other and holding takes place.
They can be used for keeping the doors and windows open or close.
They can also be used as door catch in high temperature upto 4000C, they do not loose their magnetism. They holding forces varies from 5kgs to 20 kg depending upon the sizes.