Here is the ad copy from Antec's website:
And here is Fractal's version:Externally, the SOLO II’s dual-layer 1.0 mm SECC / polycarbonate top & side panels absorb noise for exceptional sound dampening.
High density noise-reducing material for an optimal silent case - To achieve a high level of noise reduction, material with mass should be incorporated which is what we strive to achieve with the dense bitumen used on the side panels
Polycarbonate is pretty familiar stuff found in most consumer plastics, but what is the bitumen material used by Fractal? The only additional info I could find on Fractal's website is that it has a soft foam texture. I'm wondering which material is likely to be more durable in the long term.
Wikipedia says that bitumen is a form of asphalt. I'm not fond of the idea of having a layer of funky smelling insulation inside my computer. However, I really like the layout and design of the R4 but I think the materials used by Antec may be better.
I'm also considering the NZXT H2 and the Corsair 550D but I haven't figured out what materials they use in their cases. Are there any other models I should look into while I'm reading reviews?