Here’s something that hasn’t gotten much attention. The 140W power adapter that comes with Apple’s new has a subtle design change. As a result, some accessories are no longer compatible. However, not everyone has the new design.

Some early buyers of Apple’s new M5 Pro and M5 Max 16-inch MacBook Pro report that the design of the power adapter’s duckhead has changed

A teardown from shows the change, and multiple posts from customers online flag the issue.

thers have the original design — adding to the mystery behind the change.

Apple power adapters with a removable AC wall adapter, or duckhead, traditionally use a C7 connection, which resembles the shape of a pair of glasses.

The 140W power adapter that comes with Apple’s new 16-inch MacBook Pro, however, has a different connection. It’s a more symmetrical shape.

For two accessories, the new shape to break compatibility.

First, Apple’s $19 Power Adapter Extension Cable doesn’t work. It uses the duckhead shape that all other Apple power adapters with modular plugs have.

Apple used to include these in the box before removing them from the first Touch Bar MacBook Pro a decade ago.

Customers that the will not work with this new shape. Apple no longer sells the World Travel Adapter Kit on its website, but it has a detailing the product.

It’s unclear if the that Apple sells for $99 has switched over to this new model yet. Apple still lists compatibility with the Power Adapter Extension Cable.