Short answer: the Bose Soundlink Flex. It ranks #38 of 179 medium speakers by sound quality (rated 3.8/5) at $79.99 and is still sold new; the EarFun Uboom Slim ranks #43 (rated 3.7/5) and is discontinued, so it is only an option used.
The Bose Soundlink Flex is the deeper-bass option. A small, rugged waterproof speaker that survives drops and floats, with a warm, bass forward sound for casual outdoor use. Its bass reaches about 56Hz before falling 10dB, against 63Hz for the EarFun Uboom Slim. Watch for: Warm sounding with overly boosted bass which drowns out midrange detail.
The EarFun Uboom Slim is the longer-running choice. A slim, affordable waterproof stereo speaker with long battery life that doubles as a speakerphone. It is rated for 16 hours of battery against 12 for the Bose Soundlink Flex. It keeps a wired aux input, which the Bose Soundlink Flex lacks. It plays in stereo from a single unit, unlike the Bose Soundlink Flex. Watch for: Not as deep bass as others.
Buy the Bose Soundlink Flex. It is rated higher for sound quality; the EarFun Uboom Slim is no longer sold new.
Want more options? Browse the full Portable Bluetooth rankings.
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Specifications Side By Side
| Bose Soundlink Flex | EarFun Uboom Slim | |
|---|---|---|
| Price | $79.99 | $79 Discontinued |
| Ranked | #38 of 179 in Medium Size Portable Bluetooth Speakers | #43 of 179 in Medium Size Portable Bluetooth Speakers |
| App | Yes | No |
| Bass Extension (-10dB) | 56Hz | ~63Hz |
| Battery Life | 12 hours (Manufacturer specified) | 16 hours (Manufacturer specified) |
| Built-in Microphone | Yes | Yes |
| EQ | No | No |
| IP Rating | IP67 | IPX7 |
| Bluetooth Latency | 33ms | - |
| Maximum SPL | 96dB (measured by Alan Ross Reviews) | - |
| Party Mode | Yes (Bose Party mode) | - |
| Power Input | USB-C | USB-C |
| Stereo | No | Yes |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Weight | 1.3 lbs (589 g) | 1.2 lbs (560 g) |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 4.2 | 5.2 |
| Dimensions | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) | 2.6”H x 7.1”W x 2.6”D (65 x 180 x 65 mm) |
| Drivers | 1x 60mm full-range driver + 2x passive radiators | 45mm speaker drivers |
| Digital Aux Input | No | No |
| Bluetooth Codecs | SBC | SBC |
| Aux Input | No | Yes |
| Strap | Yes (built-in loop) | - |
| Amplifier Power | - | 20W |
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