A safety device for use in alpine terrain, based on the tube principle. As well as securing a lead climber, the very light Bionic Alpine Belay also allows one or two second climbers to be independently belayed, in an auto blocking mode, from the belay device. Its optimised geometry allows comfortable belaying as well as reliable blocking in the event of the second climber falling; the blocking system can be released by using a sling and the large eyelet on the device. The friction of the ropes allowed a controlled holding of lead falls, even at reduced force levels. This system suits twin, half and single ropes from 7.5 to 10.5mm in diameter.