Hello Elizabeth,
My understanding of the HC is 'High Capacity' designed for use with the modern digital and mobile phone cameras.
I also mostly use Sandisk SD Cards and when these SDHC cards first came out, whilst it did show it on the label of the actual card, it wasn't on the packaging, so of course I didn't find out it wouldn't work with the KN7 until I'd opened the package. However, I was so incensed about it I immediately took it back to the shop complete with the open packaging and complained about this fact. (in England, some retailers will refuse to take any 'software' back if the packaging has been opened) However, the assistant completely agreed with me and gave me an instant refund. He also said he would inform Sandisk about this lack of information on the cover of the packaging. I'm not saying I had anything to do with the re-think, but now, all of the SD Cards show whether they are SDHC or just plain SD - and that's the secret, make sure it only has 'SD' and not SDHC printed on it.
I was also upset to be told that the SDHC cards cannot be used with my digital Canon Camera bought in 2003 as "it is too old" would you believe. It was then suggested I buy a new one. I wont repeat my answer, but not doubt you can guess......?
Hope you're keeping well.
Audrey