Dual GTX 1080 founders

Good Morning all.

I have a quick question.

Hopefully within the next week due to a small unexpected injection of finances and of course clearance from the High commander (wife) I am looking at getting a second gtx 1080 founders to run in sli.

I bought a Alienware aurora November last year specs below

Alienware Aurora R5 Base

Intel(R) Core(TM) i7-6700K Processor (4-Cores, 8MB Cache,

16GB (2X8GB) HyperX(R) FURY DDR4 XMP at 2400MHz

850W PSU Liquid Cooled Chassis

My question / questions are what kind of SLI bridge do I need to get? is there anything I am missing that I would need to think about getting to make this work out of the box?

Thank you in advance.

Dredger