JohnE

Some info to consider.....

The orange silicone o-rings used by Gates require no lubrication, including installation.  Using silicone lubricant can not only attract dirt, but the o-ring will swell and could lead to other issues.  

Black o-rings are usually, but not always BUNA.  

The blue ones from Sea & Sea are, I think, flourosilicone. The lube they provide is compatible, while others in general use may not be.  

So....You should always follow manufacturers instructions for lubrication.  Deviations might not be pretty (and we've seen them).  

J-

The Nauticam is a large housing and traveling with it is a definite challenge. I am not sure why all of the housing manufactures insist on making such large housings for a camera that is only slightly bigger than a large DSLR. Even with a large battery pack attached it still doesn't warrant such spacious accommodation.

As David points out, heat dissipation is important when dealing with these bleeding edge cameras.  But the main driver of housing size is far more basic:  buoyancy.  

If you have an aluminum housing glove fit to the camera it would sink like a rock.  To offset that would require adding air space via foam, tubes -- whatever.  So we just make the housing larger to balance everything.  You then get more space for other things e.g. controls, cables, and your hands for service.  

J-