The Petzl I'D-S (small) is similar to the Petzl RIG but has more built-in safety features. The integrated anti-panic function and anti-error catch limit the risk of an accident due to user error. The AUTO-LOCK system will enable users to easily position themselves at a work station without having to manipulate the handle or tie off the device. Once locked, the rope can be taken up without having to manage the handle. The Petzl I'D-S works on inertia, similar to your car safety belt. When used as a lowerable ground anchor device for single-line access, the anti-panic feature means less qualified personnel can lower the climber if the need arises. Check for access rope compatibility before investing in this product.