Interior

Storage-wise, things are rather slim, but if you're serious about mini-ITX then you should be doing away with as many cables as possible and opting for M.2 SSDs or a NAS anyway. There are just two 2.5in SSD mounts and no space for a larger hard disk. But the benefit is a case that takes up less space than the already-small Phanteks Shift. The H1 is truly very small indeed.

Dust filters are included only on the U-shape panel mesh vents, for the simple reason these are the only intakes, which are via the 140mm cooler fan, PSU fan and your graphics card. It's a positive airflow situation here, with both components venting air to the sides. 

This does mean that some gets pushed down, where it's met by holes in the base, but the roof is solid. As a result, it did get noticeably warm during testing, but a lot seemed to be coming out the upper reaches of the near top-to-bottom mesh vents, too.

The cooler is your typical Asetek unit and is compatible with Intel and AMD's current mainstream sockets, i.e. LGA115x and Socket AM4, which is probably all you want to sit in there anyway given the heat loads of Intel's HEDT CPUs... even if you can find one of ASRock's X299 mini-ITX boards. This means that even a heavily-overclocked Core i9-9900K or Ryzen 9 3950X and high-end GPU aren't really going to give the 650W PSU much to worry about, although we'd maybe have an eye on the supposed Intel 10-core 10th Gen CPUs power requirements before committing funds.

 The CPU cooler has fairly short tubes so the whole contraption is easily tucked away. However, the tight fit does mean that memory needs to be 45mm or shorter, ruling out most of the RGB modules out there, not that you'd see much through the side panels anyway.