Why do you need adjustable end links? Well, they allow you to remove any preload from the sway bar. They're not necessarily required with every aftermarket bar, but they are the last step in corner-weighting the car to ensure it's perfectly neutral.
The weakest point in adjustable end links is usually the rod end (or "Heim joint") at the ends. Rod ends allow for a good range of motion and they look like awesome race car parts, but they wear over time. The speed at which they wear depends on the quality of the bearing and the environment in which you live. Some inexpensive ones have a lifespan of 6 months. There's a reason you'll never see rod ends on production cars.
These end links are custom-made for us and feature a strong and durable ball joint at each end. No worries about wear over time! Due to the very short length of this unit, you will have to disconnect it in order to adjust the length. The length can be adjusted from 60mm to 68mm (2.4" to 2.7").