E-Brakes are a safety accessory that cuts power to your kit when you apply your bike's brakes. They're required by law in some places, and generally, are a good idea.
These are high-quality long-lasting Tektro brand E-Brakes. They use a hall-effect sensor and a small magnet instead of an electro-mechanical switch.
E-Brakes are a great safety accessory, and these are premium quality.