Removing the earphones from the box to charge them, the first thing that came to mind was, “That thing it tiny… Hopefully I don’t drop it. Ever.” The charging port plug is the smallest component to any device I’ve ever used. To Fiil’s credit, they include an extra charging plug in the box, but man is it tiny, and a small tether to the earphone would have been wise.

Upon inspecting the accessories the earclips were attached along with the largest tips, and the ear fin loops removed to get the best fit. Listening periodically throughout the week, here’s what I found:

Underwhelming. Compared to my Etymotic Mc5, things didn’t sound terribly accurate, from vocals, to most instruments. Bass is significantly better than a typical earbud that sits in your ear, though not up to par with many IEMs that seal the ear canal. This may be due to the various ports on the speaker unit, and the lack of sealing power and small driver. Treble is unremarkable, without much air, though there does seem to be a peak before it gets too high to balance out the slightly boosted midbass.

They stay in fairly well with the ear loops. They also stick out quite a lot, and the cable microphonics were loud while walking around the house… Activity would seem to make this even more of a pain point at lower volume levels where the brushing sounds aren’t drowned out by music.

The body of the Carat is durable enough, though the glossy plastic attracts fingerprints. On the black version, this is noticeable, but easy enough to take care of. Cabling seems excellent from a wear and tear standpoint: Though flexible, the strain relief areas and connecting cables seem resilient.

There is some sense of presence even with these in, which should be the case if one is running. They Fiil Carat does muffle things enough to help reduce the necessary volume level if there is some background noise, though I don’t suggest using them during loud activities, as the volume will need to be used to drown out external noise.

Yes, an app is included. Unfortunately, like many other apps specific to one device, I don’t like using it, and the only mildly useful feature to me is the EQ. Hopefully this becomes more useful going forward and allows for at least a 5 band, customizable curve instead of the presets. Charge is shown, along with options for 3D sound and steps. Every time the app is launched, I have to agree to the terms of service, and click “Log in as guest.” Annoying, and not worth my time.

Several earloop fins and eartip sizes are included along with a cable cinch, all seen below, along with a small pouch to transport the earphones in. For a bit more conveniece, the earphones are magnetic and can be attached to lie at the neck when not in use:


Fiil did okay… and that’s not okay in a highly competitive market. Having a value proposition that more or less equates to, “Let our headphones change the EQ for you as you work out, and count your steps just as your phone or smartwatch can,” doesn’t seem to be useful, especially when the sound quality and usability aren’t up to par.

Using a quality balanced armature driver to improve the sound quality while shortening the distance between the ear and body of the earphone, while doing a little more homework on ergonomics and building an app that is a pleasure to use will help all around. Best of luck next time, Fiil, but Carat is not something I’d recommend.

Thanks to Fiil and OnePlus, particularly Sophie for the chance to review these. You even sent me the color I requested to match the red OnePlus cables I love, and my ThinkPad.

I received these earphones as part of a competition on the OnePlus community forums:

Questions on things not covered in the review are welcome. All photos were taken with the OnePlus 3T and can be viewed here:



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