Hello, thanks for asking though not too clear about the question but will give a better answer to my best knowlegde.
If its about what business should ECA whom you'll be referring should be involved in, I'd say any business accepted by SFI. Check here http://www.tripleclicks.com/ECA/Guidelines.php to see what products your ECA's must be selling. So long as they are not selling any restricted product you have unlimited widths to recruiting them as ECA. This is how best I can answer, good luck.
Cheers
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