This is the Tekin RX4 Hardbox Waterproof Sensored/Sensorless D2 Crawler ESC.

Tekin's RX4 Brushless Sensored ESC is designed to power your chassis past any obstacle. With massive power handling capabilities, a waterproof* design and all the customization features you'd expect from a Tekin ESC; the RX4 has you covered no matter the situation. Not only reliable, this ESC has a host of built in features like a High Voltage BEC, Drag Brake, Data Logging, Voltage Cutoffs for LiPos, HotWire 3.0 Bluetooth Connectivity and the ability to run either Brushed or Brushless motors. The RX4 defines versatility.

The RX4 Housing is a thick-walled, reinforced Hardbox design able to withstand the elements and rough environments that come with true Offroad adventuring.

Rocks, Dirt, Snow, Sand, Mud, Trail and Track; the RX4 is no-limits RC fun

Features:
HardBox Waterproof Design *
Multi-Fin High Efficiency Heat Sink and Optional High RPM Cooling Fan
QuickTune One Touch Programming
Adjustable Torque Control ***
Adjustable Throttle and Brake Frequencies ***
HD High Voltage Programmable BEC ***
HotWire Programming Port ***
Data Logging Capability ***
Sensor Checker
One-Touch Radio Calibration
On-Board Temperature Indicator
ESC Self Diagnostics with Error Codes
Fully Proportional Forward/Brake/Reverse
D2: Dual Drive Mode Technology
Brushless and Brushed Motor Drive
Sensored or Sensorless Operation
LiPo Safe with Custom Voltage Cutoffs
Sensor Plug for Precise Commutation
HDAC: High Density Copper PCB's
Ultra-smooth and Precise Throttle and Braking Control

Designed to run Tekin ROC 412 and ROC 412HD motors:
2s Lipo up to 4400kV
3s Lipo up to 3100kV
4s Lipo up to 2300kV

Programmable Features:
DB - Drag Brake (13 steps)
BS - Brake / Reverse Strength (13 steps)
LM - Torque Limiter (7 steps)
NW - Neutral Width (13 steps)
TP - Timing Profiles 5 Presets - 2 Custom
MT - Brushless Modes: Fwd/Brk, Fwd/Rev, Rev Delay
Brushed: Fwd/Brk, Fwd/Rev, Fwd/Rev Delay
VC - Voltage Cutoffs: 2S, 3S, 4S and Custom
Extensive Tuning via Tekin HotWire (sold separately)
Custom Throttle Profiles
Adjustable Throttle and Brake Minimums
Adjustable Throttle and Brake Frequencies

* Waterproof in sensorless operation only. Element Proof ESCs and Motors are specially designed to withstand water splashes and are not meant to be submerged. Included dielectric grease must be used on the sensor connections to protect them from shorting.

Specifications:
Adjustable Timing: Yes
Drive Type: Forward/Brake/Reverse
Product Height: 35.5mm (1.4 in)
Product Length: 40.6mm (1.6 in)
Product Weight: 2.65oz (75.5g)
Product Width: 50.8mm (2.0 in)
Programmable: Yes
Speed Control: Brushless - Sensor