What does Control Knobs look like on Samsung?

On Samsung it is the design shipped in One UI 8.5, shown above at full size. Older revisions are listed beneath it.

When did Samsung add Control Knobs?

Samsung first drew Control Knobs in Touchwiz 6.0, released March 7, 2016.

Samsung Electronics has shipped 24 versions of Control Knobs. Each is dated, so you can see when the design changed.

Samsung Touchwiz 7.1

Samsung shipped a new design for Control Knobs in Touchwiz 7.1, released September 21, 2016. The previous design is shown beside it.

✳ marks a release that redrew this emoji. The rest re-shipped the design unchanged.

What does Control Knobs look like on Samsung?: On Samsung it is the design shipped in One UI 8.5, shown above at full size. Older revisions are listed beneath it.
When did Samsung add Control Knobs?: Samsung first drew Control Knobs in Touchwiz 6.0, released March 7, 2016.
How many times has Samsung redrawn Control Knobs?: Samsung Electronics has shipped 24 versions of Control Knobs. Each is dated, so you can see when the design changed.