Grades Explained

Grade A
Cosmetic: Light wear and tear. May have one or few light scratches that do not catch a fingernail or tool. No cracks present on the device or display. Unnoticeable / Very Light Burn Image Allowed
Functional: Tested and Fully Functional with clean ESN and no user locks (not FMIP / iCloud locked).
Video of Samsung Grade A (https://www.youtube.com/watch?v=lsxMlPmuPUA)
Video of iPhone Grade A (https://www.youtube.com/watch?v=QAtLTdbQNJI)

Grade B
Cosmetic: Moderate signs of use on screen and housing. Deeper scratches and dents may be present from normal usage but are not considered excessive. In addition, screen burn may be present. Unknown part allowed (aftermarket part)
Functional: Tested and Fully Functional with clean ESN and no user locks (For example FMIP / iCloud locked).
Video of Samsung Grade B (https://www.youtube.com/watch?v=SNSBZJIS4WQ)
Video of iPhone Grade B (https://www.youtube.com/watch?v=YprKwMgeb3E)

Grade C
Cosmetic: More aggressive wear and tear. May have cracks on certain surface areas such as camera lens, rear lens, but not on display cover lens (Glass panel and Digitizer). In addition, screen burn may be present. Unknown part allowed (aftermarket part.) No Face ID and no fingerprint allowed, Pixel/Black dot allowed, not affecting other functionalities of the device.
Functional: Tested and Fully Functional with clean ESN and no user locks (For example FMIP / iCloud locked).
Video of Samsung Grade C (https://www.youtube.com/watch?v=mHFJwr0bOEI)
Video of iPhone Grade C (https://www.youtube.com/watch?v=2Rt5eH5wpHI)