Features :  
100% Brand New
 Input Voltage: 4.5v-28v
Output Voltage: 0.8v-28v
Current: 0a-12a 100W
IFYou Have Additional Heat Dissipation, The Power Can Reach 200w!
Work Temperature: -40~+85 Degree
Frequency: 300khz
Efficiency: 93% Max
Size: 60X60X20mm

Advantage:
Over heat protection
Short current protecion
Large current
Some Application:

it is for Step down voltage application. for example battery, power transformers, DIY adjustable voltage regulator. 24V car power laptop power supply. 12v to 3.3V, 12V to 5V, 24V to 5V, 24V to 12V etc.

Testing for reference:

Input 12V, Output 5V/10A，Efficiency 81%
Input 12V, Output 5V/6A，Efficiency 86%
Input 24V, Output 12V/8A，Efficiency 91%
Input 24V, Output 19V/6A，Efficiency 94%
Package
100% Brand New
1 x DC to DC Buck Converter High Power Step Down Car Power Supply Voltage Regulator