Ace in the Hole

Patch 2.1.0

 * : increased the chance to find an Add-on to 100 %.
 * : set the maximum Rarity of the first Add-on to  across all Tiers.
 * : added a chance to find a second Add-on of  Rarity or lower of // %.

Patch 3.6.0

 * : added the functionality to prevent Add-on loss upon escaping.

Effectiveness
The following table shows the approximate probability of obtaining each Rarity of add-on with  III, based on a sample of 450 opened chests: * In the sample, there was no second Add-on 53 % of the time.

Trivia

 * At Tier III of , all can be found attached to their respective.
 * The only exceptions to that are the, , and.
 * As of Patch 2.1.0:
 *  applies to any obtained by the effects of.
 *  can allow Survivors to find two instances of the same equipped on an Item (which is usually impossible).