The Duo-haler was an ingenious device that provided nasal inhalation of menthol, camphor, pine oil, eucalyptus and methyl salicylate in a petroleum base. The device was a simple spring clip with two cups. It was put into the nostrils, where it could be worn inconspicuously. Into the cups were placed pads wetted with the medication. The Duo-haler was manufactured in New York.
