Apple has launched a service to help users transfer a copy of their photos and videos from iCloud Photos to Google Photos.

iCloud Photos and Google Photos are two of the biggest photo storage services, each the default storage mechanism for their respective mobile operating systems. With users switching back and forth between devices, the ability to move data and photos is a vital service.

Apple has now added the ability to transfer photos to its rival’s service, although not without limits.

Some content—including shared albums, smart albums, photo stream content, live photos, some metadata, and photos and videos stored in other folders or locations—is not transferred at all.

There are also limits to the size of albums. Because Google limits albums to 20,000 photos, any iCloud albums larger than 20,000 will still be imported, but only 20,000 of the album’s photos will be placed in the corresponding Google album.

The entire process can take anywhere from three to seven days, during which Apple verifies the request is valid.