“Under very rare circumstances, a crack may form along the rounded edge of the screen in aluminium models of an Apple Watch Series 2 or Series 3,” the company said in a statement.

Apple or an Apple authorised service provider will replace the screen on eligible units that exhibit this type of crack, free of charge, the company also said.

After a slow start in 2015, the Apple Watch has become the one of the company’s most-popular products.

It’s part of a wearables business that generated US$5.5 billion in fiscal third-quarter revenue, up 48% from a year earlier.

The device faces 15% tariffs from the Trump administration starting Sunday as part of a trade war with China.