Help with sync cables

Hi!
I am very new to underwater photography and what strobes will work with what housings.

I have a Sony a7r with a Meikon housing - I also happen to have a Ikelite DS51 strobe, but I am unsure of what cord is suitable.

I thinking that this item is what I need but thought if anyone else has some better insight I would ask!

https://www.opticaloceansales.com/ikelite-single-sync-cord-ike-housing-to-sea-and-sea-or-inon-strobe.html

I'm not 100% sure that what you want is possible - certainly not with the cord that you linked. That one is designed to link an Ikelite housing to a Sea & Sea strobe, while what you need is the reverse - a cord to link a Nikonon / Sea & Sea type housing to an Ikelite strobe. At first glance, this should be suitable, but alas, Ikelite remark right there that Meikon has fitted their housings with a non-standard Nikonos-type bulkhead, which is not compatible with this cable.I don't have that housing myself, but another poster has remarked that the sync connector on Meikon A7R II housing only has two wires - this may have something to do with it.

Your least expensive option is probably to sell the DS-51 and buy a used Z-240 or YS-D1, or a new Meikon ST-100, plus Meikon's sync cord for Inon/Sea & Sea strobes. Failing that, you can look for a used Ikelite housing for your camera, plus an Ikelite-to-Ikelite cord to connect your strobe.

Thank you heaps! I will have a look at the links you have shared and might try conta ting Meikon themselves about a possible solution.

You could also look at the Ikeite optical converter:

https://www.bhphotovideo.com/c/product/1061688-REG/ikelite_4403_optical_slave_converter_for.html?ap=y&gclid=EAIaIQobChMIxrmdwZH-3AIVHLjACh0rVgWXEAQYASABEgL5dvD_BwE&smp=y

It allows you to trigger your DS-51 by optical fibre- no sync cords to deal with, it is triggered by the onboard flash.

A7 series cameras do not have an onboard flash, and Meikon housings for these cameras (all three generations) don't have a fiber optic bulkhead to use an LED trigger. Barring a very expensive housing upgrade or some very extensive DIY'ing, wired sync is the only option.