HiTec 35646W HS-5646WP Waterproof Digital Servo/Metal Gear/Dual BB Metal Gear with MP First Gear with Dual Ball Bearings Industrys First IP67-rated Waterproof Case with IP = International Protection Code and 6 = Dust Tight, 7 = Immersion up to 1M 2 Cell LiPo Capability with Programmable Circuit