These boots run true to size. I normally wear US 10.5D boots, and the 10.5D 83828s fit me quite well.

These 10D 83828s should fit someone who normally wears 10D boots, and possibly someone who normally wears 9.5D boots after replacing the given footbeds with a thicker alternative.

If these boots would be used for work in a company that helps cover the cost of footwear, let me know before buying so I can ensure you'll receive a proper receipt that can be shown to your employer.