I can't give detailed specifics about our confidentiality agreements, due to the confidentiality agreement that I've signed
But as a rough guide, some key topics to think about are:
Raw material and finished product pricing, and profit margins.
Supplier contact details
Customer contact details
Other pertinent intellectual property relating to your company (designs, marketing materials etc)
I've seen several places use a clause about general "know-how", although I'm still sceptical as to how enforceable it would actually be in court due to the obvious challenges around proof of what know-how has been acquired where.
At the same time as we first had this implemented, some of us also had non-compete clauses added, and some more substantial wording on ownership of IP, patents etc developed in the course of work duties - these may also be something you want to think about.
If your HR people aren't overly familiar with writing these types of things then it's possibly worth getting advice from a lawyer - they may (a) think of things you didn't, and (b) help with writing something that achieves the desired purpose. My solicitor burst out laughing the first time I was given a contract with these types of things in, as the wording may have made the board and HR team happy, but it wouldn't have actually accomplished much for them.