From time to time I offer Giveaways on my blog. More often than not the items given are items I have purchased myself.
On some occasions the item will be offered by a company. Whenever that is the case, it will clearly state in the post that the item is offered on behalf of a company and the company is named.
On some occasions I am the participant in highlighting an offer made by a group or company. In this case, all inquiries that those items need to be made with the group or company offering the item.