I was shopping around for a cheap bag of ferrules on eBay, and I found these:

http://cgi.ebay.com/Shimano-6mm-SIS-...QQcmdZViewItem

Simple question, are there basically standard ferrules? I ask because I'm not familiar with the "Shimano O-Ring Seal," and although these are actually FOR an SIS system, I would like to use them elsewhere as well.

As a follow-up question, should an SIS system only use these specific ferrules, or will the standard Park type I get at my LBS suffice?