It's badly designed; the holes where you connect the wires are tiny, which is trouble in a marine environment where you want a fair bit of copper on every connection. The screws that hold the wires in the connections are tiny too which makes the whole business fiddly and (at least in my case) you need a magnifying lens. Maddeningly, the screws aren't threaded to the ends, so they will fall out before they have actually cleared the space where you have to push the wire in, which is just plain poor design and requires you to take each completely out and refit it. Also, the contacts aren't numbered or labelled in any way, (that I could see) nor is there a wiring diagram with the product. I looked out the Raymarine manual which does have a wiring diagram, but it has the terminals numbered 1 to 6 which doesn't correspond to the socket (unless the numbers are in black on a black background). You can work out which is which by counting clockwise from the slot at the one o'clock position on the plug (after you've flipped it around) but there's an element of hoping for the best and I have no idea if there would be consequences to sending 12v up the sea-talk channel. Thankfully, lots of people online have had the same experience and have posted diagrams and instructions to help. All in all, for £50 it's an overpriced and shoddy piece of kit - if you only need power to your Raymarine, I'd recommend cutting the plug and socket off and fitting a well designed and substantial alternative, they're available from Force 4 for about £15.