air curtain refrigerator

hi.
please look at these pictures:
these are refrigerators with air curtain.
how air curtain in refrigerators work?


http://www.radsarmaco.com/files/8261...450-MedPic.jpg
http://www.radsarmaco.com/files/8261...440-MedPic.jpg

;)


Please help if someone has had similar symptoms or experiences with the described system.

Thank you for all information

air is blown accross the opening to try and provide a barrier between the refrigerated space and the shop to try and reduce running costs and give easy access to the products instead of plastic strips or glazed doors