100% sure! This is what I have done. I do believe and I might be wrong that Schneider distributes Lee products in the US. One more thing that I am not sure of but it is worth the try, you might be available to buy the ring directly from Schneider.
Thanks, but I already bought my ring and holder many moons ago. 
I just wanted to confirm what seemed odd to me at first, but perhaps Schneider is to Lee what Bogen is to Manfrotto.
The ring seems simple, I am surprised nobody retro engineer them. 

