When you use Braiins OS+, we collect a 2-2.5% dev fee (depending on hardware model) by directing that percentage of your hashing power to our pool. It’s up to you which pool you mine with for the remaining 97.5-98%. Note that the dev fee is never exactly the specified percentage of your total hashing power, as this number is always changing in real-time whenever you are mining. However, it will always remain within a fixed tolerance as described in the License.