A great training tool for any barista! The bottomless (naked) portafilter allows the barista to view problems that may be occurring during the espresso extraction. Baristas will know if channeling occurs making them aware that a level tamp was not made. Available and fits most E61 group heads including ECM, Expobar, Faema, Iberital, Isomac, Rancilio Silvia, Rancilio Commercial, Vibiemme, and Wega (Classic).