Actually it depends on how far thick your case is. iBlazr works good with a lot of cases, but there are still a few big ones that require an audio extension cable to allow 3.5mm (jack) connector be fully inserted into the headphone port. We do not sell those cables, but you can always purchase one in the any convenient place for you.
Here is how it looks like
Length of the cable may vary to answer your needs - basically, it can be from 1 cm long, but not longer then 100 m, depends on the quality of the cables.