I ran in to Endless Bike Company a while back when looking for American made drivetrain parts. Recently BikeRumor did a profile on the North Carolina based company itself. It seems like Endless has been through quite a bit of a journey to get to where they are now, but the products they produce are evidence that it was worth the struggle. They offer both cogs and chainrings for single speeders and 1x drivetrain riders. Check out the full article for more details on this great American made company.