Runners use these laces because they won't come untied during a race; they are made by New Balance, a running shoe manufacturer. Called "bubble laces" (the brand name is Sure Lace), they look vaguely like a garter snake that swallowed a number of small frogs.
The small bumps in the lace prevent it from coming loose in use. As we age we may not need them for running but we do need them to prevent the irritations and possible tripping caused by an undone lace.
Available in white, brown and black. It is possible to convert white into any color you want with a color marking pen.
To determine the length you need, simply measure the length of the existing shoelace.