Some items and weapons have tiers, numbered using Roman numerals to distinguish different types. Different tiers of the same item or weapon have similar overall effects, but have different credit values, cooldowns, PWR costs, or other properties. Higher-tier items or weapons are generally more powerful than lower tiers, but are not always strict upgrades, and often have higher skill level requirements for the agent using them.
The tiered items are Accelerator Chips, Buster Chips, Cloaking Rigs, EMP Packs, Paralyzers, Portable Servers, Shock Traps and Stims; the tiered weapons are Neural Disruptors, Thermal Disruptors and Volt Disruptors.
Different tiers of items and weapons can be found in Nanofabricators depending on the in-game time, with lower tiers available earlier in the campaign and higher tiers available later. Additionally, “tier III” and “tier IV” items and weapons can be found in Security Dispatch missions.
The Contingency Plan DLC adds a fourth tier for some items and weapons, which are considerably more powerful versions, but they are much more limited in how often they can be used. Each fourth-tier item or weapon has one charge per mission, which is consumed when the item or weapon is used. Once used, the item or weapon cannot be used again until the charge is replenished at the start of the next mission, or during the same mission by using a Charge Pack.