This is a (roughly) 1:18 scale single pair set of aircraft carrier arresting cable "retractable" sheaves based on the Nimitz Class aircraft carrier's arresting line setup. This item is intended for use to help your GI Joes land their Skystriker jets (once they are properly equipped with either a vintage or a modern-era tailhook, of course) on the deck of your USS Flagg or on the deck of your home-grown aircraft carrier of your choice. These sheaves are, of course, not actually retractable like the real thing but they are designed hollow on the bottom with a place to install a string or elastic band into these decorative sheaves (either tie a string around the central pillar or you can knot one end of the string and snag that knot in a slot at the back of the central pillar). With an elastic band and a screw through each sheave into the deck of your carrier, you could actually make a fairly functional set of arresting cables if you are so inclined. If you don't want to drill into your deck, you can always get by with hot glue or some sticky tack to hold these sheaves in place.
This is a single pair of these sheaves, a 3-pack (which allows you to set up a 3-wire landing strip, just a bit cheaper than buying three sets individually) is also available in my shop.