A shackle or a Link are primary locking fasteners, connecting links in all manner of rigging systems, from boats and ships to industrial crane rigging, as they allow different rigging subsets to be connected or disconnected quickly.
A shackle is a U-shaped piece of metal secured with a clevis pin or bolt across the opening, or a hinged metal loop secured with a quick-release locking pin mechanism.
Also known as Carabiners, spring hooks are a specialized type of shackle: a metal loop or spine having a spring-load or screw locking gate, used to quickly and reversibly connect components, most notably in safety-critical systems, allowing for quick attachments to either side of the tether.
These sheaths feature multiple attachment points for key rings, cord, etc. Used extensively by mountaineers, hot air balloons, sailing, construction, window cleaning, industrial rope works etc.
Other uses include Dog Leash Support, Car Bag Hanger, Tighten a Rope, Cabinet Lock for Kids, Belt Organizer, Sign Holder etc.