Battle Arms Development is now a dealer for the previously mentioned Mission Adapted Design (MAD) Hook Up. Their offering of an ambidextrous sling mount seems fitting given their commitment to ambidextrous selectors for the AR-15.
You can now save a few bucks and purchase the BAD-ASS and a MAD Hook Up together in a combo. Check out Battle Arms Development for more details on the combo.
Great combo! I have both on my AR. Quick and easy to install.