The Mi 11 67w charger is backward compatible with 55w output power charging. Millet's 67 watt charger is a charger that supports the USB PD fast charge protocol. This protocol supports the fast charge protocol charger to automatically adjust according to the charging protocol and charging power of the device being charged. Normally, the 55 watt device should also support the USB PD fast charge protocol. Therefore, using the millet 67 watt charger to charge the 55 watt device can reach the maximum charging power of 55 watts.