The slightest accidental knock and they'd fall off. Lost count of the number of cups they've broken that way.
The latest silicone seals have the right thickness stamped on them. 8 mm. As you can see at the bottom of the seal.
But that thickness is wrong. Because they are in reality 8.5 mm--too thick.
I've now bought some red ones which are of the right thickness and portafilters pointing the right way.
