Machard knots comparison
<a href="//commons.wikimedia.org/wiki/User:Rupertsciamenna" title="User:Rupertsciamenna">Rupertsciamenna</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span> (<a href="//commons.wikimedia.org/wiki/Commons:Derivative_works" title="Commons:Derivative works">derivative work</a> from <a href="//commons.wikimedia.org/wiki/File:Machard_unidirezionale.jpg" title="File:Machard unidirezionale.jpg">File:Machard unidirezionale.jpg</a> and <a href="//commons.wikimedia.org/wiki/File:Machard_bidirezionale.jpg" title="File:Machard bidirezionale.jpg">File:Machard bidirezionale.jpg</a>)