This is the Align 35-amp Brushless ESC with Governor Mode, 5-volt BEC, and the EC3 connector.  This is great for the T-Rex heli.

Features:

• Up to 35A continuous current with proper airflow
• Compatible with 2-4S Li-Po or 6-12 cell Ni-Cd/Ni-MH packs
• Dual BEC regulators
• Programmable functions, including voltage cutoff, brake, governor and more