Used to mount bottle cages on frames without braze-ons - 

These are used to hold water bottle cages on bikes without braze-ons. They work best with cages that have an elongated mounting area and only on 28.6mm dia .non-oversized frame tubes. They will not work on cages with short mounting tabs, like Nitto cages, but you can use them with VO bottle cages, it's just not a perfect fit.