Under 6401, the outer sole and upper must be joined by bonding, welding, or a similar process — not by stitching, riveting, or mechanical assembly. Footwear where the sole and upper are attached by stitching or other mechanical means, even if made entirely of rubber or plastics, falls under 6402 instead.

Yes, provided the boot meets the waterproof and bonded-construction requirements of the heading. The protective metal toe-cap subheading (640110) applies regardless of ankle or knee coverage, so height is not the determining factor when a steel toe is present.