Adjusting the length of cord lanyards is achieved by using a size adjusters, another useful piece of lanyard hardware. The adjuster is typically installed at the top behind the neck and slides up and down on the lanyard.
This type of adjuster is also know as a slide size adjuster. Pulling the lanyard material up through the adjuster raises the lower portion of the lanyard up toward your chest.
A convenience for people of different sizes allowing them to adjust the actual position of their id card or other object. The two most popular size adjusters in use are the bead and double barrel slide.