Stainless steel, aluminum and covered steel
Compare the documented material with the actual shape of the product.
Read the core and finish separately
A black finish may be powder coating over stainless steel. Check the listing for both the underlying metal and the surface finish if either matters for care.
Look up the exact aluminum model
The CalExotics Alloy Metallic Ring Medium specification identifies aluminum for SE-1370-10-2. Use the matching SKU before applying those specs to another product.
Confirm how an open-sided model is built
A silicone-covered metal core still has a rigid component. Check the maker’s instructions for that model and avoid guessing how much it will flex.