Garnish (IKEA KVARTAL system) Cart and Hook set

Recently I found myself in a situation. I needed new blackout curtain in my office. I bought some fabric, however I could not find Carts and Hook for KVARTAL, it looks like they stopped producing it.

The carts are 6th iteration so I think that I have caught most of the problems with it, such as friction and weak structure.

If you are conecting two or more KVARTALs together, have in mind that carts get stuck in the space between.