Design and features:These headphones have an integrated microphone and volume, music player function, and call connect/disconnect controls for use with paired Bluetooth devices. Additional features include three switchable EQ modes that change the tonal balance of the headphones, support for Apple Siri and Google Assistant voice commands when Bluetooth paired to devices that have those capabilities, three levels of headband tension, moisture wicking earpads that can be removed and washed, earcups that fold for ease of carrying and storage, and manufacturer claimed water resistance. This model comes with two headband tension bands of different stiffnesses, a removable headband pad, a USB charging cable, and a carrying bag. The free JLab Audio app provides various signals that are intended to "burn-in" audio devices, but otherwise seems to be a shopping link to other JLab products.
Sound quality: In its Signature EQ mode we found the Flex Sport delivers sound quality that falls in the Fair range, meaning that it has sonic shortcomings that leave a lot to be desired when listening to music but don't rule it out for dialog and communication. The overall sound can best be summarized as anemic. The bass (as in bass drums, bass guitars, stand-up bass, etc.) has good impact and goes deep, but is slightly thin sounding. The midrange (voices, guitars, horns, etc.) is slightly thin and grainy. The treble (cymbals, the upper range of violins, etc.) is extended somewhat smeared (sounds that should have a delicate shimmer sound blurred). This model does a decent job of recovering the room ambience of a recording (the sense of the acoustic space in which the audio program that's being listened to was recorded). The sound also has a good sense of liveliness and is somewhat open (sound-wise it almost seems like you don't have anything covering your ears). However, we found that the sound is not centered between the earcups when it should be - it is shifted to the left, which can give the user the impression that one of their ears is clogged - a feeling that may be disconcerting for some. The unbalance sound placement of the headphone dropped the overall score into the Fair range, otherwise if would have scored in the lower end of Good. The EQ settings do have an effect on the sound - compared to the Signature setting the Bass Boost setting increases the low bass, and the Balanced setting reduces the bass and makes the sound a bit echoey. In both the Balanced and the Bass Boost settings the sound image is still shifted toward the left.
Comfort: We found that these headphones produce a sense of pressure around the ears that ranges from light to fairly high depending on which stiffening band is used if one is used at all. As typical of on-ear models the pads might feel hot after prolonged use. Users with larger ears might find that the over-the-ear fit of the ear pads feel cramped, or that the ear pads sit on, rather than around their ears; in that case the less-than-ideal fit around the ears might interfere with the earpad seal and reduce the amount of bass heard from the headphone. Users with larger heads might feel that the headband doesn't provide enough extension so the earcups sit properly on the ears and/or that the headband puts pressure on the top of their heads. Users with smaller heads may find they can't get a good earpad seal because the ear pads gap at the top, and that the bass becomes a bit subdued. Some users might find that the headphones feel unstable and shift forward a bit and may even fall off when they lean far forward even with the firmest stiffing band. When wearing this model while walking the vibrations from each foot step can be heard faintly through the headphones.
