If they're slim, then it's because the battery inside isn't very big and it won't boost your battery life by much. (digitaltrends.com)
In fact, many users keep the wireless on their readers switched off most of the time since that significantly boosts battery life. (cnet.com)
Users can simply place their smartphones, tablets, or smartwatches on the computer's base and immediately start boosting their battery life wire free. (eweek.com)