Do you do physical distribution (CDs)?

No.  Open Book Audio manages to keep its percentages and royalties low by not navigating through the fast-disappearing world of physical distribution.  Bookstores are going out of business left and right.  Libraries, one of the last buyers of physical audiobooks, are fast transitioning to online digital distribution of audio titles.  The overhead of producing, warehousing, and shipping physical titles would require us to take a much larger percentage of your sales.   You will still maintain the physical distribution rights to your title, so if you want to sell your CDs on your own or through another distributor, you are free to do so.