Along with a small manual, also included are two earpieces, (one is a spare) that you place over the end of the earpiece. This is the difference then with most headsets, which use a hook, which you place over the ear. This instead is an in-ear headphone, which initially filled me with concern. I personally have never got on with an in-ear headphones and I have been accused by Riyad of having ‘mutant ears'. Initially then, I felt as if there was no way I was going to get on with the Invisio.
Instead of a hook, the headset is inserted into the ear and is held in place by what Nextlink calls a ‘Soft Spring'. This is actually quite a good name and refers to the extended bit of plastic that extends out of the earpiece like a small tail. This is meant to actually curl round the contours of your ear to keep the thing in place. The manual even suggest snipping off the end if it's too long, to ensure a perfect fit. It was a bit fiddly at first, but I got quite adept at putting it on quickly and once in place it didn't fall off. I did feel a little discomfort from the pressure on my ear canal I was able to keep the headset on for a whole morning.
However, don't think that because of its size it will be that discreet, it still sticks out some way from your ear, and wearing it put me in mind of Uhuru's earpiece from the original Star Trek series, though not nearly as bulky.
The headset itself has one button on the side that's used to answer and end calls. On the sides are two very small, buttons for raising and lowering volume. There are lights to indicate when it's on, but sensibly these are on the inside so you don't have to worry about wearing a naff flashing earpiece.
All-in-all, it's a very nifty bit of design from the Danish company but it doesn't stop there. Nextlink has a background in providing crafty noise cancelling technology to SWAT teams and Special Forces and as such you'd expect a good performance from the headset in the real world. The G5 doesn't actually sport the Bone Conduction Technology used in its more extreme headsets, but I had no complaints in day-to-day use.