Chek Rope RIng. Made for a friend as a gift, this ring has an inside diameter of 17.5mm ID (US size 7 1/4, UK size O 1/2). Outside diameter is approximately 21mm, the band is 7mm wide.
This ring can be available in any reasonable ring size. Please contact me with sizing info. Price will vary upon size, but will be no more than $25 for an un-polished as-shipped-from-Shapeways ring in stainless steel (see middle photo above.)