Snap BMX Products S2 Chain Tensioners.  Set of 2, Precision CNC machined from USA mill certified 6061-T6 billet aluminum.  Stylish design, fits 3/8” axles, has two screws for securing in place and 2 holes for more adjustment.  Comes with 18-8 stainless steel set screws and nuts.  Color - Gold Anodized.  Weight - 1.6 oz. per set.