The Petzl Pirana descender allows you to do quite a bit more than your average figure 8. The Pirana has three braking positions and also has two spurs for additional friction if it is need during descent. There is a much smaller connexion hole in this device than in others of its kind. The hole of the Pirana is desgned to fit a 12mm bar karabiner. When the karabiner is in position it is quite a tight fit this highly reduces the risk of awkwardly cross loading the gate of the karabiner. When using the rapid techinque where the rope passes through the karabiner there is no chance of the rope larks heading. It is possible to use the Petzl Pirana in this way due to its additional breaking options that are available. Designed for use on single ropes although can be used on double ropes but certian breaking positions may not be posible. The ideal karabiner to use with this device is the Petzl Attache screw gate or the Petzl William screw gate.