A ceiling ventilation device, mountable in an opening in a ceiling between a pair of ceiling joists, includes a pair of mounting brackets. Each bracket, attachable at its ends to a pair of ceiling joists, includes a pair of spring biased mounting tangs spaced along the bracket. A housing defines an air...http://www.google.fr/patents/US4406216?utm_source=gb-gplus-shareBrevet US4406216 - Ventilator device and mounting arrangement therefor
Ventilator device and mounting arrangement therefor
