These are so exaggerated punk rock style. A conversation piece once others notice them for sure. 
Unisex earring
Stainless Steel Hypoallergenic 
Available in 4 colors:
Pink
Black
Silver
Multi-color
Measurements: The stud itself is 1mm thick. The head of the bolt earring is 0.3" long. The back of the earring is 0.5" long. The earrings unscrew