Tough Clip Aero comes in at 1,6 mm thick making it featherlight and discreet. The thin gauge also allows the titanium to be cut with smaller gaps meaning the JRW logo is cut out and the middle prong is much closer to the outer prong to help prevent keys from accidentally slipping off. You may notice a lot more flex to the Tough Clip Aero but rest assured that the grade 5 titanium is remarkably springy and will never deform under normal use.