A climber chooses equipment according to the slope and texture of the ice. For example, on flat ice, almost any good hiking or mountaineering boot will usually suffice, but for serious ice climbing double plastic mountaineering boots or their stiff leather equivalent are usually used, which must be crampon compatible and stiff enough to support the climber and maintain ankle support. On short, low angled slopes, one can use an ice axe to chop steps. For longer and steeper slopes or glacier travel, crampons are mandatory for a safe climb.