D ( M ) in mens shoes means it's a medium width. Medium is the standard width for most shoes/boots. If you have any other questions you can always call Orthoticshop. We are open Mon-Fri 9-5pm Est. 800-309-0412. :)

C/D would mean a WOMAN's WIDE shoe. This would be narrow for a men's shoe. Men's standard width is D Measured width as a letter (or combination of letters), which is taken from a table (indexed to length and width) or just assigned on an ad-hoc basis: Examples are (each starting with the narrowest width): A, B, C, D, E, EE, EEE, EEEE, F, G (typical North American system, with the unlettered norm being D for men and B for women) 4A, 3A, 2A, A, B, C, D, E, 2E, 3E, 4E, 5E, 6E (variant North American)

Caterpillar Men's 2nd Shift6steel

Q: Are these boots waterproof, Electric Hazard rated and Puncture resistant?

They sure are water proof no doubt about that  as for puncture resistant they can hold there own as well I've stepped on nails glass and a couple of broken pipes and I've yet to feel anything...one of my Co-Workers even dropped a 25Ib. block of cement and my foot survived without a scratch.