Short answer: the Bose Soundlink Flex 2nd gen, if you are buying new. The Bogasing M4 ranks higher than it (#28 vs #37 of 172 medium speakers, 4.0/5 vs 3.8/5) but is discontinued, so only consider it used; the Bose Soundlink Flex 2nd gen is still sold new at $159. The Bogasing M4’s replacement, the Bogasing M5, is rated 3.5/5 at $52.99.
What the Bose Soundlink Flex 2nd gen gets right: Pretty much identical sounding to the 1st gen. Set against that: Not stereo.
Buy the Bose Soundlink Flex 2nd gen new; the Bogasing M4 is no longer sold new, so it only makes sense as a used find.
Want more options? Browse the full Portable Bluetooth rankings.
A 731 g stereo portable speaker with IPX7 waterproofing, a claimed 24-hour battery and a measured 99dB maximum output.
eBay
A very portable 586g, IP67-rated speaker with a clear, well-balanced midrange that keeps voices and instruments intelligible.
Amazon $159.00 eBayPrices on this page were last checked October 16, 2026 at 5:46 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 2nd gen | |
|---|---|---|
| Price | $45.99 Discontinued | $159.00 |
| Ranked | #28 of 172 in Medium Size Portable Bluetooth Speakers | #37 of 172 in Medium Size Portable Bluetooth Speakers |
| App | No | Yes |
| Aux Input | Yes | No |
| Bass Extension (-10dB) | 54Hz | - |
| Battery Life | 24 hours (Manufacturer specified) | 12 hours (Manufacturer specified) |
| EQ | No | Yes (3 band) |
| IP Rating | IPX7 | IP67 |
| Bluetooth Latency | 150ms | - |
| Maximum SPL | 99dB (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 (586 g) |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 5.0 | 5.3 |
| Amplifier Power | 40W | - |
| Drivers | 52mm speaker unit | 60mm full-range driver with passive radiators |
| Digital Aux Input | No | No |
| Bluetooth Codecs | SBC (inferred; additional codecs unverified) | SBC, AAC, aptX Adaptive |
| 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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