See: PowerStar

PowerStar have introduced the new PM-3015W ultra-high torque digital servo. Enclosed with a CNC finished aluminum casing, this mighty 30KG ultra-high torque servo will steer anything it been installed in, and the waterproof full metal case (of cause metal gears as well) will allow it to operate in extreme working conditions. Comes as a standard size servo, PM-3015W is designed for Crawlers, Buggies and Monster Trucks. It Will work up to 8.4v as its input voltage and can provide 30KG-cm torque while running at 0.1 sec/60°. Despite its high performance, it can be used in even larger applications such as 1/5 or 1/4 vehicles. A 25T servo horn is included in this package as well as all the fasteners for mounting.