Studs:

316 Surgical Stainless Steel Flat Round Blank Peg Stud Earring Settings, Stainless Steel Color

Size: about 10mm long, 5mm in diameter, pin: 0.8mm; tray: 5mm

Backs:

304 Stainless Steel Ear Nuts

Size: about 4.5mm wide, 6.5mm long, 3.2mm thick, hole: 0.7mm.

Sold in packs of 10 pairs WITH backs (20 total)