La Marzocco Removable Portafilter Spout O-Ring - Smaller
There are now two sizes of spouts due to a revision in the cut at the bottom of the portafilter. Some work best with the small o-ring, and others with the large. This smaller one measures 3.53 mm thick with an outside diameter of 14.5 and an I.D. of 8 mm and is considered to be "older".