Illusion Tunnel Plug Expander Black Stainless Steel Men Unisex Screw Earrings 12mm. These in style, illusion tunnel plug earrings are so comfortable that you won’t even feel like you are wearing earrings! They work as either men earrings or as lady earrings. These black plated anodized stainless steel 16 gauge screw earrings are 12mm in diameter. Diameters available: 5mm, 8mm, 10mm and 12mm.