Beaky,
The Z-5500 sub is a good choice if you just want to beef up the bottom end of the Eons. The sub doesn't have a handle - it is basically a cube shape with 4 flat sides, speaker at the front and electronics at the back. If you want a handle to carry it around you have either got to add one yourself, get a carry bag that fits or buy one of those computer carry strap handles (I think there is a reference somewhere on SZ to these).

I decided to 'upgrade' the box itself by adding carpet, corner protectors and handles etc. You can check out some photos here
http://www.synthzone.com/ubbs/Forum37/HTML/011419.html

Kind regards,
Mark