he 58mm group head size is a popular and standard size for espresso machines. 

However, it's important to note that not all espresso machines have this size. 

A 58mm blind filter fits with 58mm porta filters/group handles. 

The blind filter is used with water or Cafetto machine cleaner powder to clean the group head of your espresso machine properly. 

Unfortunately, we cannot provide information about the group size of your device as we do not sell or service coffee equipment. 

To use the blind filter, remove the ground coffee filter basket from the porta-filter handle and insert the blind filter. 

Add a small amount of Cafetto Machine Espresso cleaner powder and perform back flushing of the group head. 

It's essential to consult your owner's manual before using a blind filter, as some machines cannot be backflushed with one. 

Backflushing with a blind filter helps remove rancid oils that can accumulate from regular espresso extraction.

Failure to clean your machine regularly can result in two serious problems. First, the taste of your espresso can be degraded due to the buildup of rancid and bitter compounds around the group shower screen.

Second, the 3-way valve used in most espresso machine designs can become clogged or fail to function correctly, resulting in expensive repairs and inconsistent pressure during extraction.