Lava Cable TightRope Solder-Free Kit 10 red angled
I would recommend buying a cheap continuity checker as the centre core can sometimes bend when pushed in making tip to ground contact. However they are simple to take apart and straighten the centre core. I make one end - check that tip and sleeve isn't connected, then make the other end. I tightened the jack with pliers wrapped in gaffa tape to not damage the sleeve. Checking with the continuity tester all the time. So Push it in, check it, hand tighten, check it, tighten it up, check. Then the other end same process then final check tip to tip and sleeve to sleeve and make sure tip isn't grounded to the sleeve.
The little tool that comes with it isn't perfect but I eventually got the hang of it. Made them all with the tool.
Excellent solderless leads and no tools needed except what is provided and the vital continuity tester - if you soldered your own you would need a tester anyway.