AL539b is a basic OBDII & Electrical Test Tool supports all 10 modes of OBD2 test for a complete diagnosis. It features One-Click I/M Readiness Key, circuit test, starting and charging systems tests, battery test, TFT color display, and built-in speaker.

Ml529 is another basic code reader from Autel. It features a TFT color display and built-in speaker for visual and audible message cues and the patented One-Click I/M Readiness Key for quick State Emissions.It is upgraded with AutoVin functionality but cannot do AC/DC voltage test, circuit test, battery test, comparing with  AL539b. 
 
ML619 is an excellent choice for those looking for an affordable scan tool that offers OBD2 Complete Diagnostic Functions, detects faults on ABS/SRS systems, and is compatible with a wide range of vehicles. 
 
ML629 is an upgraded version of MaxiLink ML619 and AutoLink AL619. It is designed to help you to read and erase DTCs for ABS, SRS, Engine, and Transmission on most 1996 and newer vehicle models. Also, it is equipped with extensive OBDII diagnostic capabilities, which allows you to determine if a given car is ready for an emission inspection, as well as propose possible solutions for the problems identified.