PETZL Unireverso Belay Device/Descender 4" high 5" wide ULTIMATE BELAY SYSTEM: Combines a REVERSO 4 belay device and the ATTACHE carabiner for a unit that is loss-resistant and reliable. SINGLE DEVICE, MANY USES: Effective braking on half ropes (8 mm or greater diameter), twin ropes (7.5 mm or greater diameter), and on single ropes (8.9 mm or greater diameter). ADAPTED BRAKING: Increases the braking action on thinner ropes and adapts it to thicker ropes, thanks to its V-shaped friction channel. ASYMMETRICAL GROOVES: They help to increase the braking action when the rope enters the device (fall, top rope, rappel), and the fluidity when the rope exits the belay device (taking in slack) ROPE FRIENDLY: Will not kink the ropes regardless of the mode used and separates the two strands of rope when belaying and rappelling on two ropes.