What are B1 boots?
B1 mountain boots are three-four season boots, more rigid than B0, making them suitable for winter fell walking, while maintaining a light weight. B1 boots are compatible with C1 strap-on crampons. A good all-round boot, they are not recommended for climbing or more demanding winter mountain conditions.
An ideal hybrid that you can use all year round, B1 boots are versatile. Leather or fabric uppers allow breathability and flexibility. The semi-rigid midsole is designed to take C1 crampons. These boots have a flat heel and do not have the toe lips required for C2 mountaineering crampons. B1 boots are useful for mixed terrain and less technical rock routes.
What are B2 boots?
B2 mountain boots are genuine four season boots, with the rigid soles and uppers required for challenging winter mountain conditions while still retaining a small amount of flexibility for general walking. B2 boots have a heel lip making them compatible with C2 crampons.
B2 boots are suitable for mountaineering and mixed climbing. The increased thickness of the uppers in comparison to B1 adds insulation. Highly durable with wide-spaced lugs on the soles, along with a higher ankle, B2 boots provide the support and protection needed to tackle mid-grade climbing and glacial terrain. Flexible C1 crampons can be used with B2 boots but they are also compatible with C2 crampons with heel-clip bindings.