Boots for Mont Blanc are quite specific: they need to be particularly well insulated, and must also have a very rigid sole (very hard to bend with your hands) for long hours wearing crampons. Boots which will only just take a crampon (e.g. "B1" type) are not suitable as they don't provide enough support over a long period. Suitable models incluse Scarpa Manta ("B2" type) or La Sportiva Nepal Extreme ("B3" type); have a look on the internet or in a shop to get an idea, so you can compare with your own if you have them. In general we don't reccommend you buy boots specially for the trip; our hire boots have been very carefully selected and virtually never give problems, and if you really want to buy, wait until our guides are on hand to advise you.