Isopropyl alcohol is usually specified as 99.x% and not 100% because it is hygroscopic. I think it's best to get the "100%" kind. With a 91% solution, the other 9% might not evaporate and leave residue instead.
Isopropyl alcohol is made without water, only alcohol. But we are in planet Earth and the air has water in suspension (% relative humidity) so you use it in the air and the alcohol takes the water from the air, open the bottle and use asap . Can not have 100% alcohol in air in planet earth.