You don’t have to depend on just the magnet holding the K2 and the possibility of loss if you have a 600 series implant. The K2 comes with a clip to prevent this. Since I have a 600 series, I don’t wear my K2 without it being secured/ clrpped to rhe top of a shirt or to my hair.
There are a couple ofoptions to secure the K2. One is with the supplied clip that you can clip to a shirt or a tiny barrette style clip that can be used to secure to your hair. Due to the size of the K2 (the thickness), I wear my K2 on top of my hair, not tucked under it like I can with my N7 coil. The thickness of your hair is also going to affect how the K2 holds to the your head.
When activated, I received 2 N7 processors. 1 coil has a size 2 magnet and the coil I use with my N7 had a size 3 magnet. When I traded in my spare N7, I was able to keep the sxtra coil with the size 2 magnet. Since I was using a size 3 magnet, the Cochlear rep told me to go one strength level higher. So I got a size 4 in the K2. After 3 months of the size 4 K2 magnet, I found I needed more strenth than the 4 and went to a size 5. That seems to help. I would advise against wearing a K2 without a clip or barrette clip. There is also a head band with a pocket for the K2. That can be used as well.
The K2 has a rechargeable battery only. The K2 charger also serves as a dehydrator. This means you can charge and dehydrater the proccessor at the same time. Based on my mapping, I can get about 18 hours of battery life.