This is the best 2.5g servo we've found so far. If you need high torque and precision in a truly tiny package, this is the one to get. It is a digital servo so position accuracy is second to none.
This servo is available with two different connectors. The JR Connector is the standard servo plug that will work with any normal radio control receiver. The JST-SH connector is much smaller and works with the Servo TinyShield and Horizon Hobbies Ultra Micro radio control electronics. Be sure to select the correct connector for your application.