LED Meters Revisited

I previously asked (and Jack of all Trades helpfully responded) for advice in the matter of powering several LED current and voltage meters newly-installed on my boat. Jack advised that a DC/DC converter was what I needed. The meter manufacturer requires a voltage fluctuation not to exceed 5% and when operating the anchor windlass (1500 W) or when charging the3 batteries, I think that would be exceeded.

I purchased such a device for $10.00 on line. However I had anticipated 4 pins - two in and two out. The device has 6 pins. I had a search on the net for the device but got no joy. I couldn't get a hit on the name of the manufacturer.

I emailed the Vendor and asked for a data sheet. He responded by directing me to an Island Freight chat room. I didn't go there.

I should, of course, simply buy another one from known reputable supplier but I'm curious: can anyone help me to put this thing into service?

I cannot figure out how to post a photo. Manufacturer is DEXU. and the device is:

RF1212CS-2W