Short answer: the EarFun Uboom L. It ranks #2 of 177 medium speakers by sound quality, rated 4.6/5, at $49.79; the Bose Soundlink Flex ranks #38, rated 3.8/5, and costs $79.99, which makes this an easy call rather than a real tradeoff.
The case for the Bose Soundlink Flex: A small, rugged waterproof speaker that survives drops and floats, with a warm, bass forward sound for casual outdoor use. It links with other speakers (Bose Party mode), which the EarFun Uboom L cannot. The tradeoff: Warm sounding with overly boosted bass which drowns out midrange detail.
The EarFun Uboom L is the better-sounding, louder choice. A great value medium speaker with clear, natural sound, waterproofing, and a Video Mode that keeps audio in sync with video. Alan Ross Reviews measured it at 103dB at full volume, against 96dB for the Bose Soundlink Flex. It is rated for 16 hours of battery against 12 for the Bose Soundlink Flex. It supports AAC Bluetooth, which the Bose Soundlink Flex lacks. The catch: It cannot produce real low-bass rumble or fill a large, noisy space, and the top end loses some detail.
Buy the EarFun Uboom L. It is rated higher for sound quality than the Bose Soundlink Flex and costs less, which makes it the one to get unless you need something the other one does better.
Looking for alternatives? See the complete Portable Bluetooth rankings.
A small, rugged waterproof speaker that survives drops and floats, with a warm, bass forward sound for casual outdoor use.
A great value medium speaker with clear, natural sound, waterproofing, and a Video Mode that keeps audio in sync with video.
Prices on this page were last checked October 31, 2026 at 7:11 PM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
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Specifications Side By Side
| Bose Soundlink Flex | EarFun Uboom L | |
|---|---|---|
| Price | $79.99 | $49.79 after coupon UBOOMLWC |
| Ranked | #38 of 177 in Medium Size Portable Bluetooth Speakers | #2 of 177 in Medium Size Portable Bluetooth Speakers |
| App | Yes | Yes (firmware >= 1.2.6) |
| Bass Extension (-10dB) | 56Hz | 56Hz |
| Battery Life | 12 hours (Manufacturer specified) | 16 hours (Manufacturer specified) |
| Built-in Microphone | Yes | Yes |
| EQ | No | Yes (10 band, firmware >= 1.2.6) |
| IP Rating | IP67 | IP67 |
| Bluetooth Latency | 33ms | 400ms normal / 66ms low latency mode |
| Maximum SPL | 96dB (measured by Alan Ross Reviews) | 103dB (measured by Alan Ross Reviews) |
| Party Mode | Yes (Bose Party mode) | No |
| Power Input | USB-C | USB-C |
| Stereo | No | Yes |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Weight | 1.3 lbs (589 g) | 1.4 lbs (650 g) |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 4.2 | 5.0 |
| Dimensions | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) | 3.1” x 8.3” x 2.8” (78 x 210 x 72 mm) |
| Drivers | 1x 60mm full-range driver + 2x passive radiators | 2x 55mm drivers + 2x passive radiators |
| Digital Aux Input | No | No |
| Bluetooth Codecs | SBC | AAC, SBC |
| Aux Input | No | Yes |
| Strap | Yes (built-in loop) | - |
| Aux Latency | - | 216ms |
| Power Bank | - | No |
| Amplifier Power | - | 28W |
Watch Them Compared
Videos and reviews that test both speakers side by side.
- Oluv Patreon: Soundcore Motion 300 = Bose Soundlink Flex = Earfun UBoom L?
- Joy & Oluv’Sone: JBL, Bose, B&O, Sonos, Earfun, SoundCore… which portable speaker sounds best?
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