One end is flat for a comfortable fit inside the mouth, it´s made to ease the stress on your gum.
This jewellery is very easy to wear and it´s very easy to change the appearenc of it by just replacing the screw on ball. 
Material specification: PVD coated Surgical Steel
Stem thickness/length: 
1.2mm x 6, 7, 8, 9, 10mm with 3mm ball