Simply answers the question.
How to Equip a Helmet Attachment
When you reach 2 level in the battle pass premium, you will earn your first helmet attachment – UA/TYPE B1, which is described as an enhanced helmet armor and simply looks like a fiscal printer attached to a forhead. However, there is no helmet attachment socket in the basic customization menu, which is quite tricky.
To add an attachment to a helmet, you need to enter your helmet socket, where you find a tab for attachments. Each attachment is assigned to a specific helmet, so unfortunately you can’t equip it on all of your armors.
To add UA/TYPE B1, you need to select Mark V (B) amor core and then the same helmet socket (the option described “select your helmet”). Here you go, now you can equip your fiscal printer and begin your own tax enforcement. Good luck, Spartans!