Petzl Evolv Adjust
A dual lanyard with a speedy-length-adjust mechanism, specifically for aid-climbing. It can adjust smoothly from 15cm to 150cm.
This is a great advantage in aid climbing off bolts where height gain with each upwards movement is maximised, as there is little loss.
Best used with medium karabiners such as the Petzl Sm'D. Note that the Evolv Adjust is a positioning device and not an energy absorber, and therefore should not be a link in the safety chain if greater than Factor 1 falls are anticipated.