More descriptively, a Screw Pin Anchor Shackle, an attachment device used in
stage rigging.
g209.jpg
http://www.slings.com/servlet/the-84...t-Screw/Detail

Sized by the diameter of the thinnest part, at the bell, ranges from 3/16" (
WLL: 1/3 ton) to 2 1/2" (WLL: 55 tons). See also
Crosby Forged Shackles - BC Wire Rope&Rigging.