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The short answer
Bose SoundLink Flex Portable Speaker (2nd Gen) wins this comparison. Choose it if sound quality comes first. Bose SoundLink Flex Portable Speaker (2nd Gen) has the higher sound-quality rating in GearLab’s matched tests: 7.5/10 versus 4.8/10.
Bose
A compact speaker that floats and adjusts its sound when you change its position. IP67 protection and a built-in microphone suit outdoor listening and hands-free calls.
Bettr Score
82/100
Ultimate Ears
A small poolside speaker that floats, with 360° playback and up to 14 hours of battery life. Outdoor Boost and Podcast Mode cover music outside and spoken audio.
Bettr Score
63.8/100
| Bose SoundLink Flex Portable Speaker (2nd Gen) | Specification | Ultimate Ears WONDERBOOM 4 |
|---|---|---|
$149 | Reference price | $99.99 ✓ Winner |
12 hours | Advertised battery life | 14 hours ✓ Winner |
1.3 lb | Weight | 14.82 oz ✓ Winner |
IP67 | Ingress protectionTie | IP67 |
4 | Durability tierTie | 4 |
5.3 | Bluetooth versionPersonal preference | 5.2 |
No | Can charge another deviceTie | No |
No | USB audio inputTie | No |
No | Auracast or compatible broadcast pairingTie | No |
Yes | Floats in waterTie | Yes |
Yes ✓ Winner | Speakerphone | No |
The buying advice
Choose Bose SoundLink Flex Portable Speaker (2nd Gen) if sound quality comes first. Bose SoundLink Flex Portable Speaker (2nd Gen) has the higher sound-quality rating in GearLab’s matched tests: 7.5/10 versus 4.8/10.
Choose Ultimate Ears WONDERBOOM 4 if tested battery endurance matters most. Ultimate Ears WONDERBOOM 4 has the higher battery-endurance rating in GearLab’s matched tests: 5.6/10 versus 4.6/10.
Bose SoundLink Flex Portable Speaker (2nd Gen) has the higher sound-quality rating in GearLab’s matched tests: 7.5/10 versus 4.8/10. Ultimate Ears WONDERBOOM 4 has the higher battery-endurance rating in GearLab’s matched tests: 5.6/10 versus 4.6/10. The recorded reference-price difference is $49.01.
Bose SoundLink Flex Portable Speaker (2nd Gen) has the higher sound-quality rating in GearLab’s matched tests: 7.5/10 versus 4.8/10.
Ultimate Ears WONDERBOOM 4 has the higher battery-endurance rating in GearLab’s matched tests: 5.6/10 versus 4.6/10.
Bose SoundLink Flex Portable Speaker (2nd Gen) has the higher volume rating in GearLab’s matched tests: 6.6/10 versus 3.8/10.
Ultimate Ears WONDERBOOM 4 has the higher portability rating in GearLab’s matched tests: 8/10 versus 7/10.
People's Pick
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eBay — New
In stock · checked Oct 30, 2026
Price needs rechecking. Confirm at the retailer.
$94.99
Item price · shipping unknown
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eBay — New
In stock · checked Oct 30, 2026
Price needs rechecking. Confirm at the retailer.
$58.49
Item + shipping · before tax
$58.49 + $0.00 shipping
We may earn a commission when you buy through links marked “Affiliate link.” This does not change your price or our scores. How we earn
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