Neutrik NL4FX speakon connectors have been discontinued. I am now using the REAN RLS4FC speakon connector which is a company of the Neutrik Group. Last photo.
 
Here is brand new, hand braided Schmitt Custom Audio High Level Sub-woofer Jumper Cable 3ft in length, designed for subs that feature linking the high level output of one sub to the high level input of another. Example: REL SIX-PACK. 
 
This cable consists of 2 REAN RLS4FC Speakon connected by 3 hand braided  12 gauge  pure stranded copper. each strand sealed in pvc coating with completed braid dressed in Snake sleeve.

Schmitt Custom Audio Cables for the "Serious Listener"
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