The LILIN M Series camera range comes in 2 different variants.
M Series 3 digit part code:
These M Series cameras come with the basic features and no advanced features such as audio support, IVS or Advanced IVS features.
M Series 4 digit part code:
These M Series cameras can support advanced feaatures such as, advance alarm features, IVS, alarm inputs out outputs (Model specific, always check the datasheet to confirm supported features on each individual specific camera).