are a trade name for a range of storage media. They tend to be fairly pricey and are well-regarded.
I suspect the format for the Raymarine upgrade will be an SD/MMC card - the trouble is that there are now mini and micro-SD cards out there, used mainly in mobile phones.
The main types of flash memory cards now stand at about 11 so you need to get it right.
yes as previously said sandisk are a highly regarded (and at the upper end of the price range) manufacturer of memory products.
Raymarine recommend then because thats probably what they tested and certified the system on, we use memory products on some of our systems (critical non - marine) and we find that one manufacturers product will work where others will not, its all down to the timings and response that the device expects, and depends on the tolerance of the host device.
I have used many different types of CF card in my C80 and A65 without any issues, from what I have found they are not fussy, and these days most of the memory devices on the market are branded items from a very small OEM base anyway.
Glad you got a another cheaper CF card to work on your C80 and A65 but I tried 2 different cards on my E80 without success and ending up having to buy a Sandisk one to get the upgrade to work.