If you have your lip pierced, you know it can sometimes be a struggle finding body jewelry that will be comfortable and will stay in place. The most secure kind of labret is a screw-in type, with either external threads on the post or internally threaded so the head screws into the shaft.
Another option is to wear a labret made of flexible material, such as Bio-Flex or PTFE. This type of body jewelry is light-weight and the head does not screw into place but pushes into a tube that can be cut to fit almost any lip snugly. Although these push-in labrets are not as secure as the screw-in variety, they offer the benefits of light-weight and adjustable length.