These rings fit on the outer rim of cardboard spools to allow you to use cardboard POLYMAKER spools in your Bambu Lab AMS.
Measured with caliper and adapted to the latest version of POLYMAKER cardboard spools from 2024
It's just the right size so you can close your AMS perfectly, it fits very well
0.4 Nozzle. Less than 5 grams of filament and 9 minutes of printing on X1C
Enjoy It ;)