This is a tiny very fine ring stock for stackable rings. The wire is flat on one side and covered in a row of textured dots on the other.

Type of Metal - Copper or Brass or Bronze or Nickel Silver,
Grade of Metal - 1st Grade,
Width - 1.5mm x .0.7mm,
Measurement - 2 foot piece,
(#6) (18g) Rodaja 3