Quality: 1/10 Silver-filled, which means that the outer 10% of each item is .925 silver. These items have a brass core. The silver is mechanically bonded to the brass. The result is much thicker than silver plating. This process make the head pins much less expensive than solid sterling silver, and the difference in quality is impossible to see with the naked eye.
Unlike silver plate, which can wear off quite quickly, silver filled will keep its beauty through years of daily wear. Just use the same precautions you would with real silver jewelry - don't expose to harsh chemicals, and when not in use, store in a dry, airtight bag or container.
Measurements: 19mm long, 22mm wide. The wire is 20 gauge (.032") thick. The ball is 3mm in diameter and the loop has an inner diameter of 2mm.