This mount with an SO239 connection is made to support the SS34+ Telescopic Whip, which screws into the mount when it is deployed with the SS34+ Guying Kit.
How to attach options:
SS34+ Mount
$59.00
Mount for the SS34+ Whip
Options
1 × 2-40M, 34' 6" Telescopic Element
Availability: In stock
$139.00