The thread adaptor simply screws into the ocular or objective end of the scope and presents a female thread that accepts the new style metal flip-up covers and accessories.
Thread adaptor for connecting the new Hawke Metal Flip-Up covers and sunshade accessories to PRE-2015 Sidewinder scopes.
Now you can upgrade your PRE-2015 Sidewinder from having Screw-in Metal Covers to having Metal Flip-up Covers and Honeycomb Sunshades.