Magnified view of the grooves of a 45 rpm vinyl record (<a href="https://en.wikipedia.org/wiki/Gic%C4%83_Petrescu" class="extiw" title="en:Gică Petrescu">Gică Petrescu</a> - <i>Cântece de pahar</i>, <a href="https://en.wikipedia.org/wiki/Electrecord" class="extiw" title="en:Electrecord">Electrecord</a> EDC 590).
The red lines mark one millimeter.
<a href="//commons.wikimedia.org/wiki/User:Alex:D" title="User:Alex:D">Alex:D</a>
<span class="int-own-work" lang="en">Own work</span>