Connecting rings: Round (0.040" or 0.048") or square (0.047") rings. [0.048" = 18ga., 0.040" = 19ga.]
Punched rings: Stainless, Titanium, Brass, or Bronze

For comparison, here is a list of weights and (tentative) prices for what a long aventail would be for several material choices.
[Welded Ring Mat. / Punched Ring Mat.]
Square Stainless / Stainless - $245, 4.5lb.
Round (0.048") Stainless / Stainless - $245, 4.3lb.
Square Stainless / Titanium - $275, 2.9lb.
Round (0.048") Titanium / Titanium - $375, 2.4lb.
Compare to the 5/16" x 0.048" ring size:
Stainless - $225, 3.7lb.
Titanium - $375, 1.8lb.
If I can get enough interest I'll go ahead and order the two most popular choices.
-Ben
