30mm Lightweight QD Rings?

[KMO]

The subject line seems easy enough, but finding some lightweight (aluminum) 30mm quick-detach rings to fit the factory rail on my Ruger Mark III pistol has not proven easy thus far. There are plenty of heavy-duty steel rings out there, but I'm trying to minimize weight on my pistol, so aluminum works better. The quick-release type is important to me because I want to retain the ability to use my iron sights without breaking out the tools. Anyone else found these critters?

Maybe these?

http://www.midwayusa.com/viewProduct/?productNumber=245520