Some four years after Apple publicly unveiled its vision of free-placement wireless charging in AirPower — and two years after the device was cancelled — the company is reportedly continuing work to bring the technology to market.

Specifics are unknown, with sources saying only that the device would operate “similarly” to AirPower.

Announced in 2017, AirPower was Apple’s attempt at creating a charger that served its entire mobile device ecosystem. The project was ultimately cancelled in 2019 after suffering multiple delays, with later reports claiming Apple was unable to overcome issues related to overheating.

That said, Apple regularly files for and receives patent grants for technology that would underpin a device like AirPower.

Apple is also researching wireless charging technology that works at greater distances than modern inductive charging solutions like Qi and its own Apple Watch system, Bloomberg reports. The tech could be based on a long and diverse string of patents covering long-range wireless charging methods, the earliest of which go back nearly a decade.

Development of the system appears to be ongoing, as the report says it will likely take several years for the effort to result in a shipping product if Apple chooses to move forward.