20x20 pixel square, outlined in black and filled in white.
The original uploader was <a href="https://en.wikipedia.org/wiki/User:Val42" class="extiw" title="wikipedia:User:Val42">Val42</a> at <a href="https://en.wikipedia.org/wiki/" class="extiw" title="wikipedia:">English Wikipedia</a>.
Transferred from <span class="plainlinks"><a class="external text" href="https://en.wikipedia.org">en.wikipedia</a></span> to Commons.