A food-grade silicone o-ring is used with the Robot portafilter spout on the Robot - Manual Espresso Maker. From time to time, the silicone o-ring may require a quick rub of a food-grade lubricant, such as Dow 111. Apply just enough Dow 111 to give the o-ring a 'sheen.' The portafilter spout should fit snugly in the portafilter body. If they are too loose, clean the o-ring, as there may be excess lubricant, or replace the o-ring. Item: Robot Portafilter Spout O-Ring Product size: Approx. ⌀38.7mm 2.65mm (Thickness) Product weight: Approx. 2g Colour: White Material: Silicone rubber Included in the package of Robot - Manual Espresso Maker? Regular Robot Yes, 1 is installed on the portafilter plate and 1 as spare Barista Robot Yes , 1 is installed on the portafilter plate and 1 as spare Care and use: Do not remove the o-ring from the portafilter spout unless you plan on replacing it, removal may damage the o-ring permanently.