Short answer: the Bose Soundlink Flex, if you are buying new. The Bogasing M4 ranks higher than it (#28 vs #38 of 178 medium speakers, 4.0/5 vs 3.8/5) but is discontinued, so only consider it used; the Bose Soundlink Flex is still sold new at $79.99. The Bogasing M4’s replacement, the Bogasing M5, is rated 3.5/5 at $52.99.
Both need a mode switch to sound their best. The M4’s cons recommend its super bass mode for the most balanced sound, since the default mode runs with a boosted, harsh, thin treble. The Flex doesn’t have a mode to switch, and our notes describe it as warm with overly boosted bass that drowns out midrange detail.
The Flex’s real selling point is Bose’s durability: IP67 rated, rugged enough to survive drops from several feet, and it floats.
Buy the Bogasing M4 for the better ranking and lower price. Buy the Soundlink Flex if Bose’s ruggedness specifically matters to you.
Looking for alternatives? See the complete Portable Bluetooth rankings.
A budget waterproof stereo speaker with long battery life, an aux input, microSD playback and pairing with a second unit.
A small, rugged waterproof speaker that survives drops and floats, with a warm, bass forward sound for casual outdoor use.
Prices on this page were last checked November 5, 2026 at 10:30 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
| Bogasing M4 | Bose Soundlink Flex | |
|---|---|---|
| Price | $45.99 Discontinued | $79.99 |
| Ranked | #28 of 178 in Medium Size Portable Bluetooth Speakers | #38 of 178 in Medium Size Portable Bluetooth Speakers |
| App | No | Yes |
| Aux Input | Yes | No |
| Bass Extension (-10dB) | 54Hz | 56Hz |
| Battery Life | 24 hours (Manufacturer specified) | 12 hours (Manufacturer specified) |
| EQ | No | No |
| IP Rating | IPX7 | IP67 |
| Bluetooth Latency | 150ms | 33ms |
| Maximum SPL | 99dB (measured by Alan Ross Reviews) | 96dB (measured by Alan Ross Reviews) |
| MicroSD Playback | Yes | - |
| Power Input | USB-C | USB-C |
| Stereo | Yes | No |
| Omnidirectional | No | No |
| TWS | Yes | Yes |
| Weight | 1.6 lbs (731 g) | 1.3 lbs (589 g) |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 5.0 | 4.2 |
| Amplifier Power | 40W | - |
| Drivers | 52mm speaker unit | 1x 60mm full-range driver + 2x passive radiators |
| Digital Aux Input | No | No |
| Bluetooth Codecs | SBC (inferred; additional codecs unverified) | SBC |
| Dimensions | 3.1”H x 8.4”W x 2.5”D (80 x 214 x 63 mm) | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) |
| Built-in Microphone | - | Yes |
| Party Mode | - | Yes (Bose Party mode) |
| Strap | - | Yes (built-in loop) |
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