Like some electronics, this linear motion Pico servo doesn't like running at over 5V. Even slightly less is better. This adapter board adds a bit of voltage drop to a 5/6V system to make your servo happy.
Looking for 802.15.4 Zigbee-like device with smarts? XBee with more features? Check out Synapse modules! Small, low-power, 2.4 GHz plug-in transmitter-receiver modules, with an extended range up to three miles and power consumption as low as 2.5uA.