The XRotor Pro series of ESCs from Hobbywing have been optimized for multi-rotor use.

With their special core program for multi-rotor greatly improved throttle response and software specially engineered for 
Compatibility with disc type outrunner motors they offer unsurpassed smoothness and control.

All settings except the timing are pre-set, making using the XRotor Pro series very simple and versatile.
Crosstalk from the extra-long signal wires is effectively reduced by twisting the wires instead of laying them parallel which again, helps to simplify installation and improve the flight characteristics of your multi-rotor.
Most flight controllers are compatible with the XRotor Pro series which supports signal frequencies of up to 621Hz (anything over 500Hz is non-standard.)
The high performance of the drive chip is enhanced further by the use of extra low-resistance MOSFETs that also allow high currents to be held stable for longer.

A unique feature of the series is the Driving Efficiency Optimization (DEO) function. This significantly improves throttle linearity and driving efficiency by automatically braking and quickly reducing the motor speed when decreasing the throttle amount. This can improve the manoeuvrability and stability of your multi-rotor and improves the efficiency of the ESC as well as reducing its operating temperature.

Please note:
Throttle range - The XRotor Pro 40A 3D Muti-rotor ESC does not support throttle range calibration because this range is fixed at 1100~1940µs

Forward & Reverse 3D Flight - The throttle ranges from 1067µs to 1860µs (the neutral position is at 1463µs, +/-2µs is the dead band), 1466µs-1860µs (that is from the neutral throttle position to the maximum throttle position) corresponds to the forward 0%~100% throttle. 1067µs-1460µs (that is from the neutral throttle position to the minimum throttle position) corresponds to the reverse 0%~ 100% throttle.

Please see the manual in the files tab below for details of these advanced features.

This ESC is intended for 3D multi-rotor use only and does not support normal throttle operation.

Features:
• Super-efficient ESC
• Slim design for fitting inside tubular arms
• Driving Efficiency Optimization function
• Long leads for simple installation
• Programmable items: DEO function

Specs:
Constant current: 40A
Burst Current: 60A (10 seconds)
BEC Mode: No BEC (OPTO)
Lipo Cells: 3~6S (11.3~22.6V)
Power lead length: 280mm
Signal lead length: 370mm
Motor lead length: 75mm
Motor connectors: 3.5mm bullet
Size: 66 x 22 x 11mm
Weight: 50g

Included:
Hobbywing XRotor Pro 40A 3D OPTO Muti-rotor ESC
Heat shrink tube
Manual