Abalakov thread

The Abalakov thread, also called a V-thread, A-thread or zero thread, is an ice protection technique named after its inventor, the Soviet climber Vitaly Abalakov. It is a common way for an ice climber to protect themselves and to build an abseil anchor, because it is easy to create, does not require sacrificing expensive gear, and can be very safe when used properly. It is often used on multi-pitch ice climbing routes. Because of its safety and convenience it is considered one of the most significant innovations in ice climbing, since it greatly widened the range of possible routes and improved the safety of abseiling.