buckled closed. This offered a great improvement in control, but increased the risk of injury in the event of an accident. Alpine Modern alpine ski boots have rigid soles and attach to the ski at both toe and heel using a spring-loaded binding. The interface between boot and binding is standardized by ISO 5355, which defines the size and shape of the hard plastic flanges on the toe and heel of the boot. Ski boots are sized using the Mondopoint system. Front-entry Front-entry (or "top-entry", rarely "overlap" or "Lange") boots have been the primary boot design for most of the history of downhill skiing. The design evolved from existing leather boot through several steps. In 1956, the Swiss factory Henke introduced the buckle boot, using over-center levered latches patented by Hans Martin to replace laces. Laces spread the load across a number of eyelets in the leather, whereas the buckles concentrated the load at only a few points. To spread it back out again, the boots featured C-shaped flaps that stretched over the opening where the laces would be, to the side where the buckles were located. These had the added advantage of also helping block snow from entering the front of the boot. Beginning around 1960 Bob Lange experimented with ways to replace leather with plastic. Early examples used a lace-up design, but in 1964 he combined a new, more flexible polyurethane plastic with the overlapping flap and buckle system from Henke to produce the first recognizably modern ski boot. Production examples appeared in 1966, and when Nancy Greene started winning races on them, the plastic boot became a must-have item. Replacing leather with plastic dramatically improved stiffness and control, along with durability and warmth (leather boots had a way of soaking through, which led to wet, frozen feet). Over time the cuff around the leg evolved upward, starting just over the ankle like leather boots, but rising to a point about half way to the knee by the 1980s. Only minor changes have occurred to this basic design since then. Almost all modern front-entry boots consist of two sections, one around the foot, and another around the lower leg. These are joined by rivets/rotating joints near the ankle that allows the leg to pivot forward, but not to the sides. This allows excellent control by transmitting even the smallest lateral movements of the leg to the ski. However,