Credit: Kaitlyn Cimino / Android AuthorityTL;DRWe’ve spotted documentation and a rear render that confirms Samsung is working on the Galaxy Fit 4 with model number SM-R391.The device likely features a Goodix GH3036 optical sensor module for low-power heart rate and sleep tracking, along with Bluetooth Low Energy support.The rear render shows a device that is near-identical to the Galaxy Fit 3.Samsung appears ready to refresh its entry-level fitness-tracking lineup with the Galaxy Fit 4, a direct successor to the Galaxy Fit 3. We’ve spotted documentation and a render of the Galaxy Fit 4 that confirm the upcoming wearable is well into development, picking up where the Galaxy Fit 3 left off, and lending weight to earlier reports that a Galaxy Fit 4 would arrive this year.According to information we’ve reviewed, Samsung is working on a new fitness wearable with model number SM-R391, explicitly designated as “FIT4” in some documents. Here’s what the back of the device looks like: