Cogito, ergo sum
These are the anti-grav boots seen in UT, they give the player the ability to jump up to 2.5 times their normal height, and reduce falling damage for large distances when used.
There are jump boots in UT2003! Epic has a static mesh for them but I don't think the mod is included with the game to make them work (ie. you'll just be able to pick them up but not be able to do anything special with them) Maybe someone could set that up. I can't remember what thread the boots are found in...all I remember is looking at some of the static meshes that come with the game and there it was, so I'll look that info up and post it when I get a chance. OMGTTFS