Cnc'd 6061. Black. From website: Designed for use with quick release skewers or bolt on axles. They have bosses built in to catch a quick release axle so you don’t have to use spacers or washers. This design also keeps the tensioners in line with the dropout, so they will not twist when tightened. The single screw is offset in the direction of rotation so it actually tends to be stiffer than a larger screw central to the slot.
Last but not least, they are equipped with a bottle opener built in. on the drive side, the bottle can be opened with the bike right-side-up. On the non drive side, the bottle can be opened when the bike is upside down. This is done to accommodate easy-access alcoholism from any angle. These are one of the lightest tugs on the market, if not the lightest. All hardware is stainless steel. Also works as a bottle opener.