The Shim Spacer for Group Head Gasket 0.8mm is compatible with machines that use a standard 58mm portafilter, and is designed to fit underneath your group head gasket to effectively increase your gasket thickness by 0.8mm. If your portafilter handle is clocked too far to the right when engaged, this handy shim may be exactly what you need to return the handle to a more ergonomic position.