Apple Inc. in December 2017 finally admitted what people had known for years: older iPhone models were intentionally slowed down over time, theoretically as a means to preserve the devices’ batteries. After some public backlash, the global tech giant offered something of a fig leaf in the form of $29 battery replacements, a discount from the original $79 price.

On Wednesday, Apple announced it would retroactively refund some money to people who bought out-of-warranty replacement batteries for certain iPhone models before the discount went into place in January. According to the Apple support website, anyone who is eligible for the refund will be notified via email by no later than July 27.

Basically, all this does is give anyone who paid $79 for an out-of-warranty battery replacement before Dec. 28 access to the same discount as anyone who got one after that date. The significance of that date is that it is when Apple announced the discount in the first place.

apple Apple will refund some people who bought replacement iPhone batteries in 2017. The Apple logo is displayed on the exterior of an Apple Store on February 1, 2018 in San Francisco, California. Photo: Justin Sullivan/Getty Images

Customers who got their batteries replaced at an “Apple authorized service location” such as an Apple Store are eligible for $50 worth of electronic credit. Anyone who is eligible will get the money either via a digital transfer of funds or some free credit on the credit card that was used for the original battery transaction.

In short, if someone paid $79 for a battery before Dec. 28, they can get $50 back for free before the end of 2018 as long as they fit into Apple’s eligibility guidelines. It only applies to iPhone 6 phones or later models.

The controversy over Apple’s planned obsolescence of older iPhone models stemmed from pressure by Congress. Apple stated in a February letter to Sen. John Thune of South Dakota, who is chairman of the Senate Commerce Committee, that it might look into offering rebates to customers.

“For advanced technologies like an iPhone, consumers rely on clear and transparent disclosures from manufacturers to understand why their device may experience performance changes,” Thune said in February. “[Apple] has acknowledged that its initial disclosures came up short.”