What component can be an alternative to tandem prusiks for a hard mechanical belay rope grab?

Gibs are designed specifically for use as a mechanical belay system, providing a secure grip on the rope when loaded. They function similarly to a prusik knot by firmly gripping the rope when weight is applied, making them ideal for hard mechanical belay scenarios. Gibs allow for controlled descent and can be easily released when the load is removed, which aligns with the needs of a rescue operation. This makes them an effective alternative to tandem prusiks, which, although reliable, do not offer the same level of mechanical advantage and ease of use under load as gib devices.

In contrast, figure-eight devices and Yates rescue descenders serve different purposes, primarily focusing on rappelling or lowering systems rather than functioning as a mechanical belay tool. While these devices are critical in rope rescue techniques, they lack the specific gripping mechanism that gib devices provide when a quick, secure belay is needed.