Skyhook (climbing)

A skyhook is a piece of climbing equipment

Climbing equipment

A wide range of equipment is used during rock climbing. The most popular types of climbing equipment are briefly described in this article. The article on protecting a climb describes equipment commonly used to protect a climber against the consequences of a fall....

, a very small hook which gives hold on small protrusions or watery and slippery grips.
They are most often used for placements, often extremely marginal, in aid climbing

Aid climbing

Aid climbing is a style of climbing in which standing on or pulling oneself up via devices attached to fixed or placed protection is used to make upward progress....

, although they also feature in some extreme free routes. Additionally, the skyhook can be attached to the harness, thus allowing the climber to rest, or held in one or both hands to hold a grip.