These aerobars, or tri-bars as they're alternatively known, are good for getting a more aerodynamic position on pretty much any bike that has regular handlebars. These bars have plastic spacers that make them suitable for fixing to handlebars of either 31.8mm or 26.0mm diameter. The arm rests are attached to the aerobars, so there's no hassle with getting these mounted separately.
More details at the Profile Design website.