You need a 'faucet wrench':

About $6 US bucks in most locations...

Here is a link that might be useful: Faucet Wrench

I've found a better picture of the hose nut.
http://www.sanliv.com/flexible-tube-m10-x-f38-f05
This is tiny; no facet wrench I've seen would work. It would have to be eyeglass-screwdriver size. Plus it is set in the base of the faucet by 1", so no level access to it. Plus it is right up next to the other hose so even if I could get one in I couldn't get the other. I can't even get needle nose pliers close. I'll try to send a picture today of what I'm talking about.

Here is a link that might be useful: tiny hose nut

You use a faucet wrench on the hex portion of the hose end if the faucet is already installed.

If it is a new unit, you use a regular wrench and attach the faucet end before mounting the faucet.

It is probably around 7/16 inch.

Metric wrenches are normally only in even millimeters.

It should be sticking out since it is set well back from the sealing surfaces.

One again, there is no way to get a faucet wrench in here. I barely got these tiny angle needle nose pliers in, and I have no leverage to turn the tiny bolt. Please click the link to see the pictures.
I can't express enough how small this is. And the bolts are at the bottom where the needle nose tips are. The part of the hose above just spins. I've never heard of any tool that can get in here. There are two o-rings, one is below the surface while the other you can just see. But these have to be turned a couple more rotations to seal them, and I see no way of making them tighter. Unless there is a micro faucet wrench I don't see how. My standard faucet wrench is not even close to small enough.

Here is a link that might be useful: vessel faucet lines

Hello Kellyllek,
How did you end up solving the problem of tightening the flexible hoses that were recessed into your faucet? I have the same exact problem and am trying to figure this one out. Thanks.
Tim

The double o-rings mean that the nut does not have to be all that tight.

The seal is form the o-rings, not threads.

It looks like you would need something like an 'ignition' wrench. These are small wrenches that you can get in packs from Sears and some other places. You would tighten these into the faucet base prior to installing the faucet into the sink top. And not that tight since you would strip the Orings.

Ok got photos hope this helps everyone including me. I am pretty good too.

Wow comments from 10 years ago but oh