The Head-Direct RE0s I got were from the first production batch. These ship without a box, but with the final bundle which includes the following: big double flange tip, small double flange tip, small to large single flange, five sets of spare filters.
The selection of tips is reasonably good. You do not get a foam tip which can be a problem for some. If you are interested in foam tips you can get some aftermarket ones made by Comply. The model that fits the RE0s is called the T400 (Ultimate Ears version).
As a new thing the RE0s now ship with five sets of spare filters. This means that you do not have to buy filters for a long time, unless you have really nasty ears.
The body of these new in-ears is made from aluminum, and looks great compared to the older Head-Direct in-ears which feature a much less fancy plastic casing.
Looking at the in-ears from the ear on out you can see just how small the earphones are compared to the oversized double flange that Head-Direct makes.
From the side you can see just how simple the base construction is. The sound hole is about the same size as that featured on Ultimate Ears in-ears. This also means that you can fit Ultimate Ears tips on the RE0s and vice versa.
The sound hole has a little indent which is there in order to hold the silicone tips in place. As you can see on the two pictures above, the filters are made of some kind of fabric which has some random fibers sticking out. The filters are user replaceable and the whole removal and installation process is really simple. The type of filter used is acoustically transparent unlike that used on many armature based in-ears, where they are used to dampen the highs to a certain degree.
On the back of the casing there are two small holes, however, one of these is not drilled through even though it looks like it at first glance. The hole is incredibly small, barely visible on the picture above (red rectangle).
The cable entry into the earpieces is made of rubber! This means that it dampens the cable transmitted noise. Compared to the old RE1s and RE2s this is a step in the right direction, as some might remember they had a plastic barrel type cable entry which did little to dampen microphonic noise. Another benefit from having a rubber cable entry versus a hard one is that the rubber one can be bend somewhat to facilitate a better wearing comfort.
Another noteworthy improvement over the RE1s, looking apart from the improvements on the performance side, is the cable. The mini jack has been changed to a more rugged design with a big rubber stress relief on it, compared to the heat shrink strengthened one on the RE1s. The cable itself has a softer coating, with a bit more texture than the old cable on the RE1s and RE2s. The y-split is the same, although it looks a bit better on the RE0s finish wise.
Size wise the new Head-Direct RE0s are pretty much average. The shell is roughly the same volume as that of the Future Sonics Atrios. The balanced armature based Sleek-Audio SA6 is much smaller.