Depending on which version you choose, the Apple Watch Series 4 typically retails at either $399 (40mm) or $429 (44mm) in the US. For a limited time only, though, Amazon is offering both of these models with pretty hefty discounts which bring the Series 4 down to its lowest price since launch.
Starting with the larger 44mm model, the offer currently available on Amazon translates into a 12% discount. It applies to the Space Gray Aluminum Case variant and can be purchased with either the Black Sport Loop or Black Sport Band. Also worth pointing out is the fact that these models include GPS only – the version with LTE isn't on sale at the moment.
In regards to the smaller 40mm version, Amazon's discount equates to a slightly larger discount of 13%. In this particular case, it applies to both the Silver Aluminum Case and Space Gray Aluminum case, although there are some limitations. The former can be purchased only with the Seashell Sport Loop, while the latter is available with the Black Sport Loop and Black Sport Band. Once again, the model on sale only includes GPS.