The AGN Vixen can experience loss of barrel alignment of a few centimeters when pressure is applied to the shrould either by holding the shroud or resting it against a support.

This washer fits snugly into the small space between the shroud and the block and stabilises it, similar to the FX barrel tension.

Edit: it appears that the holes are not for air but for a pin socket to remove the cap. This only makes installation easier as the holes do not need to line up 😀

Print in PETG, 20% infill and 0.2mm layer height.