These are the points that stick out in front of your boots. For ice, the points should be vertically-oriented, which does less damage to the ice. On snow, most climbers want horizontally-oriented front points, which provide a larger surface on which to stand. Choosing the correct frame depends on which boots you have, as well as which discipline you want to emphasize. Rigid is best for ice and mixed climbing, with a stiff leather or plastic boot.
Flexible crampons are the old standard for everything.
These work well on snow with most any boot. To use this style you must have a sole that is designed to accept them. The down side to strap-on crampons is the amount of time and energy it takes to put them on and take them off. Grivel crampon G10 . A lightweight, universal crampon designed to meet classical demands.