Apple on Monday unveiled its AirPods Pro earphones with active noise cancellation. According to John Gruber of Daring Fireball who yesterday published his first impressions of the new earbuds, Apple will sell the AirPods Pro replacement tips at four bucks a piece.

AirPods Pro ship with three pairs of flexible silicone ear tips that Apple claims were designed to conform to the contours of each individual ear. Their primary purpose is creating a seal in order to block out outside noises, which helps with active noise cancellation.

In a true Apple fashion, AirPods Pro even include a feature called Ear Tip Fit Test that tests the quality of the seal to identify the best ear tip size for them. To help with that, each earbud also has an inward-facing microphone that measures the sound level inside your ear. Algorithms compare the data from the microphone to what’s coming from the speaker driver to detect whether the ear tip is the right size or should be adjusted to create a better seal.

Gruber lays out how it works:

Also in the Bluetooth settings is the Ear Tip Fit Test. It’s very easy. Put the AirPods Pro in your ears and start the test. It plays a song for about five seconds and decides whether you have a good fit with the current size tips. There’s nothing ’smart‘ about the silicone tips themselves — the AirPods Pro don’t ‘know‘ which size tips you’re currently wearing. The Fit Test just tells you if the current ones in your ear are a good fit.

For me, the default medium tips feel best and the Ear Tip Fit Test consistently agrees. For my son, the medium tips felt uncomfortable and the Fit Test agreed they weren’t a good fit. For him, the small tips felt better and the Fit Test agreed. According to Apple, many people have differently-shaped ears and might need a different tip size for each ear, and if that’s the case the Fit Test will suggest it.

According to Gruber, swapping the tips is easy, but “it takes a bit more pull than I expected to pop them off.” He adds the tips seem rugged.

Should they ever break or you happen to lose them, it’s great knowing that at just $4 a piece you certainly won’t have to pay the Apple tax when getting replacement tips.

Thoughts?