Funny you should mention!
Mine just arrived today (5-6 week wait) I snatched them out of the mail box on my way to work tonight. customcarryconcepts.com $13.00 each. (Postage was included when I ordered) My application, is to run full size M&P 9 mag's (17+1) in my M&P9c. (12+1).
Thanks again to Wyatt Earp!