I tested the new Ikelite #4118.1 sync cord connecting Inon Z220 to Ikelite CP5K housing today and am fairly happy with it.
The finish quality is poor, looks like someone has gripped the Inon end in a vice leaving sharp edges and burrs standing up just where the oring passes over when removing and the plastic locking nut is very roughly finished.
It only transmits the trigger signal so only provides manual flash and the focus light and laser are not operated through the sync cord.
On the positive side you can turn the internal coolpix flash off meaning that in low battery mode the LCD does not turn off whilst recharging the flash. My internal flash definitely does not fire when turned off.
It's great to be able to hand hold the Inon, and the focus light, laser and sync cord all work if you select optical/slave setting on the flash.