We’re less than a week away from Apple announcing its first-ever foldable iPhone. A new supply chain report today says that Apple’s “extremely high quality control standards” have led to a much slower ramp for iPhone Ultra production so far.

iPhone Ultra production status

According to Nikkei Asia, Apple is currently making “a few hundred” iPhone Ultra units per day. This could make it “challenging” for Apple to meet market demand for the device.

The report says that Apple added an extra trial run of iPhone Ultra production in August to “ensure the phone can be mass-produced according to its specified design.” This decision reportedly delayed actual commercial production of the device “for weeks.”

In particular, Apple is said to be focused on improving the production yields of the “surface flatness and the performance of the hinge.”