A non-magnetic stainless; very hard and rust proof, even in salt water. Lettering is deeply engraved.
Steel hanging tags do not have or need a grommet to reinforce the hole. Only plastic tags have a metal grommet.
On CollarTags, the engraving is color filled. On stainless steel hanging tags, it is not. Here is how you can DIY color fill your engraving:
Clean the tag surface to remove all traces of dirt and oils. Then paint the entire tag surface: epoxy paint is best, enamel paint or nail polish will work, or a Sharpie Marker can be used but does not last nearly as long as paint. Before the paint dries drag the tag across newspaper to remove most of the surface paint but being careful not to remove the paint in the letters. After the paint dries buff the tag with 00 Steel Wool to remove any remaining surface paint.