Apple said its new 35W Dual USB-C Power Adapter, which went on sale late last week, can automatically adjust power output based on the type of connected devices.

A new support document explains that when devices are plugged into both USB-C ports on the charger, the (relatively modest) 35W output is split “depending on their power requirements.” In practice, this means that MacBooks, iPhones, and iPads take precedence over Apple Watches and AirPods.

For example, if you connect both a MacBook and an iPad, the power is shared equally, with each device receiving up to 17.5 watts. But pairing one of those high-priority devices with an Apple Watch or an AirPods case means a 27.5W/7.5W split. Note that all of these numbers have a very important “before” prefix added to them; your mileage may vary.

Apple adds that the fastest way to charge is to focus on one device. “If any device needs more power, disconnect the other device and its charging cable from the power adapter,” the article explains.

Apple’s dual charger has been rumored since early April and finally went on sale last week. In addition to the standard charger, there is a compact version that is more suitable for those on the go. Both versions are 35W and cost $59. (UK readers are only offered the large version, which costs £69 with a UK plug.)