This is a demonstration of what NetSpeed=B might look like on a device with a DPR of 1.5. In the left column is the 330px high-quality thumb, and in the right column is the 220px low-quality thumb. The zoom column shows the effect of DPR or zooming. In the 1x row, if you are viewing this page on a desktop with DPR=1, the thumbnail is 220px as requested by the author of the page. In the 1.5x row, this is roughly how the image looks on our DPR 1.5 phone, if you stand back from the screen far enough. In the 2x row, how it might look with a bit of zooming (which users commonly do if they want to see the image detail).

Zoom NS=A NS=B