I lost the spacer, so I was looking for substitutes.
It is hard to find what aluminum is made of which length, thickness and inner diameter are perfect. Because the length and the thickness were perfect, the inner diameter was small, but I bought it and used the drill to expand the hole to 6 mm. Because it is made of aluminum, it is easy to shave, not much trouble, you can make something perfect.
It is even better if there are several inner diameters, but it is nothing to do.
There seems to be nothing goods. Those with the same dimensions were difficult to obtain at home centers, etc. However, it was difficult to purchase it but it was very easy to purchase as a monoterror. The quality is good. no problem.