It's a pain to solder up barrel jacks and plugs, so these screw-terminal based versions are very popular for repurposing DC power supplies to other applications!
After you've thrown out your broken & crushed wassizthingy, you're usually left with the power adapter. Another power adapter for the junk drawer. Wouldn't it be nice to put it to some use, except for that funky useless 46 pin X-shaped proprietary connector. Grrr. Darn user-hostile hardware.
BUT, what if you could snip off the funky connector and replace it with something familiar, and reliable? Yup, here's just the perfect solution!
These screw-terminal 2.1mm male/female socket connector sets fit the purpose exactly! Snip the wire, measure the polarity, and match them into the labelled terminals for traditional "tip-positive" configuration. Use them for extending the power wires going to your Freeduino board! They are also handy for power going to your stringxels or stripxels.
These are sold in matched plug-and-socket sets.