This connector from Koolance connects two graphics cards with a spacing of one PCI slot.

Deep black, Koolance's answer! In the highest quality, just as with every product from Koolance. The black finish covers every bit of the surface and looks like it has been cast into the metal. The unique surface finish makes these fittings a true eye-catcher for your system!

The connection nipple can be adjusted in length, both ends can be adjusted independently to allow installation between the two water blocks. Even multiple water blocks can be linked in a row with these connectors. The thread length of the connector is only 4mm, allowing water blocks to be connected without the use of spacer rings.

Detailed dimensions can be found here

Even more details regarding mounting can be found here

Technical specifications:
Material: Nickel plated brass
Colour: Black
Thread size: 1/4"
Thread length: 4mm each

Extent of delivery:
1x Connector