Firmware in Borderlands 4 is a set-bonus system that randomly appears on non-weapon gear. Each piece of gear can carry one firmware “set,” and equipping multiple items with the same set unlocks stronger bonuses.

  • Eligible gear: Repkits, Ordnance (Grenade or Heavy Weapon), Class Mods, Energy Shields, and Enhancements.
  • Guns do not roll firmware.
  • Firmware begins dropping from loot after about level 25.

Only five gear slots can carry firmware at once, which naturally leads to a 3+2 approach: max one set at three pieces while activating the first two bonuses from a second set.

How set bonuses stack (and why five slots matter)

  • 1 item with a set grants its first bonus.
  • 2 items with the same set unlock the second bonus as well.
  • 3 items with the same set unlock all three bonuses for that set.

Because you have five firmware-capable slots, a common configuration is three pieces of one set (to reach the powerful third bonus) plus two pieces of another set. For example, three pieces of God Killer for sustained damage after elite kills, plus two pieces of Deadeye for accuracy and crit damage.

Tip: Firmware is rolled randomly on drops. If you’re targeting a specific set, the most reliable path is simply killing lots of enemies and checking gear routinely.

Transfer machine: move firmware onto the gear you actually use

After finishing the main story, you gain access to Firmware Transfer Machines in major towns. These let you extract firmware from one item and apply it to another of the same type (Repkit to Repkit, Ordnance to Ordnance, etc.). Level and rarity don’t matter for the transfer.

  • Cost per transfer: cash plus 100 Eridium.
  • The donor item is destroyed during transfer.
  • The recipient keeps the new firmware, but that firmware can’t be extracted again; you can overwrite it later with another donor if you choose.

Note: This is why it’s smart to stash pieces with valuable firmware even if their base stats aren’t great—you can move that set later to a best‑in‑slot item of the same type.

All Borderlands 4 firmware sets and bonuses (1–3 pieces)

Firmware set 1 piece 2 pieces 3 pieces
Action Fist Melee damage +15% Action Skill damage +10% On melee kill, Action Skill damage +25% for 8s
Airstrike Splash radius +20% Splash damage +20% On kill, drop a missile strike on nearby enemies
Atlas EX Gun mode switch speed +20% Gun damage +10% while an Atlas Target Lock is active On killing an Atlas Target‑locked enemy, automatically lock another nearby enemy
Atlas Infinum Gun fire rate +5% while an Atlas Target Lock is active Guns with Atlas‑licensed parts gain +10% damage Atlas Target Locks are infinite unless you swap guns
Baker Shield capacity +10% Repkit cooldown duration −15% Max health +25%
Bullets to Spare Gun fire rate +5% Gun magazine size +20% Gun fire rate increases by 50% of magazine size
Daed‑dy O' Gun mode switch speed +25% Gun magazine size +15% On mode switch, gain +20% damage and +20% fire rate for 5s
Deadeye Gun accuracy +30% Gun critical damage +25% Each critical hit grants +15% crit damage per stack (max 5) for 10s
Gadget Ahoy Ordnance cooldown duration −15% Ordnance damage +20% Ordnance kills grant +20% damage for 15s
Get Throwin' Ordnance damage +10% Splash radius +20% Grenades and Tediore thrown guns have a 50% chance to spawn homing missiles
God Killer Damage dealt to Badass enemies +10% Damage taken from Badass enemies −10% On killing a Badass, damage dealt +20% for 60s
GOOJFC Action Skill cooldown rate +10% Action Skill damage +15% Action Skill cooldown rate +20% more
Heating Up Gun reload speed +20% Overheated shots before breaking +50% with CoV‑licensed parts Gun damage +25% while overheating with CoV‑licensed parts
High Caliber Projectile speed +25% Gun damage +10% Bullets pierce enemies
Jacked Zoom‑in speed +20% Hyperion gun shield capacity +25% Hyperion gun shields have a 30% chance to ricochet projectiles
Lifeblood Repkit healing +10% Lifesteal +5% On kill, regenerate 10% of max health
Oscar Mike Gun reload speed +10% Gun damage up to +20% based on how empty the magazine is After reloading, gun fire rate +30% for 4s
Reel Big Fist Melee damage +15% Additional melee damage +25% Melee kills trigger a nova for 200% melee damage
Risky Boots Below 35% health: damage taken −30% Below 35% health: movement speed +35% Below 35% health: damage dealt +100% and lifesteal +5%
Rubberband Man Damage reduction +5% Lifesteal +5% Bonuses from this firmware are doubled
Trickshot Gun reload speed +5% Gun critical damage +10% Critical hits have a 50% chance to refill 1 ammo to the current magazine

Picking sets for common playstyles

  • Melee burst: Reel Big Fist for nova on kill, paired with Action Fist for Action Skill synergy.
  • Crit‑centric gun builds: Deadeye stacks crit damage on every crit; combine with Trickshot for uptime.
  • Splash and thrown builds: Airstrike and Get Throwin' add radius, damage, and on‑kill missiles.
  • Manufacturer synergy: Atlas EX/Atlas Infinum for Target Lock chaining; Jacked for Hyperion gun shields; Heating Up if you lean on CoV parts.
  • Low‑health aggression: Risky Boots flips defense into massive damage when under 35% health.
  • Boss/elite focus: God Killer translates elite kills into a long damage window.
  • Survivability staples: Baker and Lifeblood add capacity, cooldown, lifesteal, and on‑kill healing; Rubberband Man doubles its own benefits at three pieces.

Firmware is the late‑game glue that turns a strong build into a specialized one. Use the five-slot limit to your advantage—lock in a three‑piece core that defines your playstyle, then layer in a two‑piece that smooths reloads, cooldowns, or survivability. If a drop shows the set you need, keep it. The transfer machine ensures that good firmware never goes to waste.