This band has a comfortable oval cross section. If you look closely at this ring you will see a subtle line running around the perimeter, marking the parting line of the mold.
The shibuichi veriant features a silver lining, to prevent the metal from staining your finger. The brass version is un-lined, and for most folks it will leave a stain on the finger its worn on. If desired this can be prevented, by painting the inside of the band with nail polish.
First model is wearing a BRASS ring.
Second & third models are wearing SHIBUICHI rings.