When it comes to performance, the Quicksilver cable pulley knows how to clean house. Each wheel has two ball bearings inside, giving it a faster ride while generating less heat. The dual pulley also features 2" hardened stainless wheels, and a clip-in slot for up to three carabiners. The sideplates are split apart for easy application to an existing cable. For cable up to 1/2" in diameter, and speeds up to 120mph.