Glass with a surface film of transparent reflective aluminium which reflects a percentage of the incident radiation; different grades reflect given percentages of total radiation, from 20% to 85%. It can be useful for privacy as well as for heat control; it should be remembered that from the lit side such glass appears to be a mirror, so at night can give a false sense of security while giving a clear view from outside. (As it does not depend on absorbing the incident radiation heat-reflecting glass is more effective than heat-absorbing glass).