Helmet

Alternate Helmets are different versions of the Warframes' original helmets. They have different designs on aesthetics, such as the addition of jiggle-bones (dubbed by Digital Extremes as "Dangly Bits") which was introduced in the second helmet series.

These helmets are considered as cosmetic items, as such they cannot replace original helmets in the Warframe's crafting process as a component. Prime Warframes use the same alternative helmets as their normal counterparts, and can also use the base helmet of their normal counterpart (regardless of whether the player owns the base Warframe).

AcquisitionEdit

Helmets can be bought for ‍75 in the 'Equipment' section of the Market. Additionally, their blueprints can be acquired via the Nightwave Offerings.

Once a helmet has been built in the foundry, it cannot be sold again. So building duplicates will clutter your Inventory. This also counts for helmets you automatically acquire from building Warframes and selling those since you'll keep the helmet.

EquippingEdit

Alternate helmets can be equipped in Arsenal using the "Appearance" tab when modifying a Warframe. They can be unequipped by reapplying the default skin.

ArcaneEdit

At first release, each alternate helmet had stat modifications attached to them, which boosts one of the Warframe's attributes while penalizing another. With the introduction of Nekros in Update 10, upcoming alternate helmets do not affect the stats of Warframes. As of Hotfix 13.2.3, all helmets with stat modifications are replaced with stat-less versions of the helmets in the Market and as a Nightwave Offering.

Helmets with stat modifications, now known with the prefix Arcane, can only be obtained through the Trade System. Only completed helmets can be traded, not blueprints. Previously, players could buy conversion blueprints from the market for 1,000‍1,000 to convert completed Arcane helmets to stat-less ones, but these blueprints have since been removed. By converting an Arcane helmet to a stat-less helmet a player can own two of a stat-less helmet instead of one.

Stat increases stack additively with other effects, always granting the same absolute effect:

Net value = Base value * ( 1 + effect_other + increase_helmet )

Stat decreases stack multiplicatively with other effects, always granting the same relative effect:

Net value = Base value * ( 1 + effect_other ) * ( 1 - decrease_helmet )

As an example, the Arcane Aurora Helmet gives Frost +25% armor and -5% health.

This is always an absolute increase of +47.5 armor, which could be a ~+11.9% or +25% relative increase with or without Steel Fiber, respectively.
It is always a relative decrease of -5% health, which could be a -37 or -15 absolute decrease with or without Vitality, respectively.