I have bought both the V2b and the V4 trackers from Valetron, and both are working nicely. It took me a little while to figure out the settings, but what was missing in documentation was well compensated by awesome support from the seller. The trackers came preconfigured to upload positions to Valetron's servers, which was a good way to make sure everything worked, before switching to my own MQTT setup. They have inbuilt GSM and GPS antennas, but also uFL connectors if you need to mount the antennas externally.
I would totally recommend this tracker and the seller.