A putting aid to increase a golfer's accuracy on the green is disclosed, comprising a short leg and a long leg hingedly secured to the short leg. The long leg is provided with a plane mirror and the short leg is rigidly secured to the under-surface of the peak of a standard cap worn by the golfer and...http://www.google.es/patents/US4307885?utm_source=gb-gplus-sharePatente US4307885 - Golfer's sighting aid for putting
