More descriptively, a Screw Pin Anchor Shackle, an attachment device used in stage rigging.
Sized by the diameter of the thinnest part, at the bell (AKA the bow), ranges from 3/16" (WLL: 1/3 ton) to 2 1/2" (WLL: 55 tons). For more, see http://www.thecrosbygroup.com/products/shackles/screw-pin/carbon/crosby-209-carbon-screw-pin-theatrical-shackles/ . The most common size for arena rigging is 1/2", with 5/8" used for 2T points.
Sometimes abbrev. as SPAS. There are other types of shackles, but above is by far the most common in our industry.
Sized by the diameter of the thinnest part, at the bell (AKA the bow), ranges from 3/16" (WLL: 1/3 ton) to 2 1/2" (WLL: 55 tons). For more, see http://www.thecrosbygroup.com/products/shackles/screw-pin/carbon/crosby-209-carbon-screw-pin-theatrical-shackles/ . The most common size for arena rigging is 1/2", with 5/8" used for 2T points.
Sometimes abbrev. as SPAS. There are other types of shackles, but above is by far the most common in our industry.