Hmm, it doesn't look the same as the "quick lock" Thurso surf fin which works for bluefin, irocker and some other brands. I saw another one on Amazon with a clip that says it's compatible with Roc, but not one without sorry.

When I click on your ROC link, it says it's in stock though? I doubt the ones on Amazon will be much less than $24 .. I paid $20 for my replacement there.