Asso Coffee Magnetic Dosing Ring

It does what it says, and the height is a good balance for most grinders. But the magnets are not very tight so there is some jiggle. There is also thick flange that goes over the inside of the portafilter. While this ensures grounds stay in the portafilter, it blocks using WDT to prep ground under that flange and you end up with a ring of unsifted grounds around the edge of the portafilter. Expected more for the price.

Keeps all my coffee in place while grinding and using the WDT

I've been using the Asso short ring daily for about a week now and it excels in form and function in my setup (my grinder is a modified Mini Mazzer, with the portafilter fork removed to allow adequate room for a dosing cup).
It has just the right magnetic attraction to securely adhere to the portafilter during use, while allowing it to be easily removed without spilling grounds. I use it in the following three ways:
1. When dosing into the portafilter directly - here it helps to catch all the grounds and minimize waste
2. For grounds distribution prior to tamping - it's easily big and secure enough to allow a vigorous stirring with a WDT tool without spills
3. When held over a dosing cup (as standby for a speedy second espresso) - again reducing spillage.
I was initially concerned about which size to choose, but experience shows that the short ring ticks all the boxes in my particular setup.

The dosing ring is very well built, constructed and manufactured. The main downside if the inner ring sits inside the portafilter, creating a line around your espresso pick before tamping. I find it’s great for getting the grounds into the portafilter but I wouldn’t distribute the grounds with the ring on.

It’s an expensive piece, I had just anticipated being able to distribute the coffee as well.