Wega/E61 Soft 8mm Group Head Gasket
If your portafilters are worn, they may be engaging too far to the right (and if you don't want to buy new portafilters), you may want to consider purchasing one of the thicker gaskets.
customer service and pricing could not be better. the gasket is a perfect fit. recommended.
This gasket fit perfectly in my Expobar Office Pulser machine. By far the best price, and delivered promptly. A-plus.