Natural flavors are a proprietary blend of natural ingredients used to enhance the flavor of our fresh foods. (freshpet.com)
Those data were much easier to obtain than actual user numbers, which are proprietary information. (sciencemag.org)
From the picture, it looks like an external device, so we wonder if that means that there's a proprietary interface added to the guts of the system you purchase it with. (cnet.com)