Scarpa Manta is a good example of a B2 boot. B3 Technical mountaineering and climbing boot are designed to have a rigid midsole and upper to provide support when climbing. Their stiff sole provides a platform to fit any type of crampon including totally rigid C3 ice climbing crampons. Crampons Crampons are made for different purposes - walking, mountaineering and ice climbing and need to be compatible with the boots they are fitted to so they work in harmony. Even relatively stiff boots can flex and the crampon has to be able to flex and twist to stay safely on the boot.
Crampons have two components which define their use and hence their grade.
The metal spiked base and the strapping or binding system. They are generally made as a hinged flexible 8 to 10 point crampon with or without front points attached with straps. Recommendation - The Grivel G9 typifies this grade of crampon. If in doubt get advice from your specialist retailer. C2 Articulated multi-purpose mountaineering crampon with 10 or 12 points including front points.