Short answer: the Bose Soundlink Flex. It ranks #36 of 144 medium speakers by sound quality, rated 3.8/5, at $79.99; the Earfun Uboom Slim ranks #41, rated 3.7/5, at $79. The price gap is small enough that the sound-quality ranking should decide it.
Why pick the Bose Soundlink Flex: IP67 rated; rugged enough to survive drops from several feet and floats. Watch for: Not stereo.
Why pick the Earfun Uboom Slim: Excellent pricing, strong waterproof build (IPX7), good battery life (16 hours), smooth sound with volume compensation, speakerphone capability. Watch for: Not as deep bass as others.
Buy the Bose Soundlink Flex. It is rated higher for sound quality, and the $0.99 you would save on the Earfun Uboom Slim does not close the gap.
Want more options? Browse the full Portable Bluetooth rankings.
Specifications Side By Side
| Bose Soundlink Flex | Earfun Uboom Slim | |
|---|---|---|
| Price | $79.99 | $79 |
| Ranked | #36 of 144 in Medium Size Portable Bluetooth Speakers | #41 of 144 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 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 |
Related Speaker Comparisons
More top alternatives to Bose Soundlink Flex:
- Bose Soundlink Flex vs Earfun Uboom L
- Soundcore Motion 300 vs Bose Soundlink Flex
- Soundcore Motion+ vs Bose Soundlink Flex
- Soundcore Boost “upgraded” 2021 vs Bose Soundlink Flex
- Bose Soundlink Flex vs Minirig 4
Prices on this page were last checked September 26, 2026 at 11:14 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.
As an eBay Partner, we may be compensated if you make a purchase.
The Two Speakers In Full
Bose Soundlink Flex: $79.99 Amazon eBay
Newer model: the Bose Soundlink Flex 2nd gen, rated 3.8/5.
Pros: IP67 rated; rugged enough to survive drops from several feet and floats. Around 12 hours of battery at moderate volume. Measured bass extension of 56Hz (-10dB).
Cons: Not stereo. Warm sounding with overly boosted bass which drowns out midrange detail
Full Bose Soundlink Flex review and specifications →
| App | Yes |
|---|---|
| Aux Input | No |
| Bass Extension (-10dB) | 56Hz |
| Battery Life | 12 hours (Manufacturer specified) |
| Bluetooth Codecs | SBC |
| Bluetooth Latency | 33ms |
| Bluetooth Version | 4.2 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 7.9” x 3.5” x 2” (201 x 90 x 52 mm) |
| Drivers | 1x 60mm full-range driver + 2x passive radiators |
| EQ | No |
| IP Rating | IP67 |
| Maximum SPL | 96dB (measured by Alan Ross Reviews) |
| Omnidirectional | No |
| Party Mode | Yes (Bose Party mode) |
| Power Input | USB-C |
| Stereo | No |
| Strap | Yes (built-in loop) |
| TWS | Yes |
| Weight | 1.3 lbs (589 g) |
- Links
- Reviews, Comparisons and Sound Samples
- Joy & Oluv’Sone: Bose Soundlink Flex 2nd gen vs Flex More from Oluv’Sone →
- Alan Ross Reviews: Bose Soundlink Flex Review! vs JBL Flip 6 and JBL Charge 5. Travel heaven?? 🤞 More from alanrossreviews →
- Joy & Oluv’Sone: Bose Soundlink Flex 2nd gen vs Flex
- Alan Ross Reviews: Beats Pill vs Harman Luna vs Bose Flex vs Soundcore Motion Plus
- Alan Ross Reviews: Tribit Xsound Mega vs the world! (JBL Charge 5, Bose Flex, Sony XB33, LG PL7) 👍
- Alan Ross Reviews: Bose Soundlink Flex vs Soundcore Boost vs Bogasing M4 - cheap or Bose?
- Alan Ross Reviews: Tribit Stormbox Flow has deeper bass than the Bose Flex but………..
- Jay’s Straight Up Reviews & More: Tribit Stormbox Flow vs Soundcore Motion 300 (LDAC) 😵 Budget Bose Soundlink Flex "Inspired" Speakers More from JaysStraightUpReviews →
- Oluv Patreon: Soundcore Motion 300 = Bose Soundlink Flex = Earfun UBoom L?
- Alan Ross Reviews: Bose Soundlink Flex or JBL Flip 6 (eq adjusted) or Denon Envaya - best speaker for travel!
- Alan Ross Reviews: Bose Soundlink Flex or Beosound A1 (1st gen) - ultimate compact speaker 😇
- Alan Ross Reviews: Bose Soundlink Flex or JBL Flip 6 (eq adjusted) or Denon Envaya - best speaker for travel!
- Jay’s Straight Up Reviews & More: Tribit Stormbox Flow vs Soundcore Motion 300 (LDAC) 😵 Budget Bose Soundlink Flex "Inspired" Speakers
- Patricio Benadon: Bose SoundLink Flex vs. Mini 2 SE. Music audio quality sound test. Listen 4 different genres!
- Patricio Benadon: Bose SoundLink Flex vs. Mini 2 SE. Music audio quality sound test. Listen 4 different genres!
- Danny Pops: BEST Bose Speaker?? Bose Soundlink Flex vs micro, Color II, and revolve + More from DannyPops →
- Alan Ross Reviews: Bose Soundlink Flex vs Minirig MK3 and Marshall Emberton - best bluetooth speaker?
- Joy & Oluv’Sone: JBL, Bose, B&O, Sonos, Earfun, SoundCore… which portable speaker sounds best?
- Alan Ross - The Anti Shill!: Small speaker, mighty sound, The Flex gen 2 shatters physics!
- Head-to-Head Comparisons
- Bose Soundlink Flex vs Bose Soundlink Flex 2nd gen
- Bose Soundlink Flex vs JBL Charge Essential 2
- Bose Soundlink Flex vs Tribit Xsound Plus 2
- Bose Soundlink Flex vs Huawei Sound Joy
- Bose Soundlink Flex vs Teufel Rockster XS
- Bose Soundlink Flex vs Cleer Audio Scene
- Bose Soundlink Flex vs Soundcore Motion 100
- Bose Soundlink Flex vs Tribit Stormbox Pro
- See all 117 comparisons
Earfun Uboom Slim: $79 eBay
Pros: Excellent pricing, strong waterproof build (IPX7), good battery life (16 hours), smooth sound with volume compensation, speakerphone capability. Measured bass extension of ~63Hz (-10dB).
Cons: Not as deep bass as others. Warm tuned, peaks in the mids and lower treble, rolled off upper treble
Full Earfun Uboom Slim review and specifications →
| Amplifier Power | 20W |
|---|---|
| App | No |
| Aux Input | Yes |
| Bass Extension (-10dB) | ~63Hz |
| Battery Life | 16 hours (Manufacturer specified) |
| Bluetooth Codecs | SBC |
| Bluetooth Version | 5.2 |
| Built-in Microphone | Yes |
| Digital Aux Input | No |
| Dimensions | 2.6”H x 7.1”W x 2.6”D (65 x 180 x 65 mm) |
| Drivers | 45mm speaker drivers |
| EQ | No |
| IP Rating | IPX7 |
| Omnidirectional | No |
| Power Input | USB-C |
| Stereo | Yes |
| TWS | Yes |
| Weight | 1.2 lbs (560 g) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Earfun Uboom Slim vs Xiaomi Sound Outdoor
- Earfun Uboom Slim vs Bose Soundlink Flex 2nd gen
- Earfun Uboom Slim vs Bose Soundlink Revolve+ II
- Earfun Uboom Slim vs Tribit Xsound Plus 2
- Earfun Uboom Slim vs Soundcore Boom 3i
- Earfun Uboom Slim vs Soundcore 3/Soundcore Select 2
- Earfun Uboom Slim vs Sony ULT Field 3
- Earfun Uboom Slim vs Xiaomi Sound Party
- See all 16 comparisons