Apr 19, 2026 21:00:00

Review of the '400-SP125' portable waterproof Bluetooth speaker, which can be used without worry even if submerged in water, such as in the bath or pool.

The ' 400-SP125 ,' a portable Bluetooth speaker that is

waterproof to IPX7 standards and can withstand submersion, was released on March 3, 2026. We were able to get a real unit as a prize in GIGAZINE's Spring Giveaway Campaign , so we put it to the test to see if it really is waterproof.

Enjoy music freely with a waterproof body! We've released a waterproof speaker that can play for up to 24 hours, so you don't have to worry about water or time.
https://direct.sanwa.co.jp/contents/news/item/400-SP125BL.html

400-SP125DG Bluetooth Speaker, Waterproof IPX7, Portable Wireless 6W, Outdoor, Bathroom Use, Deep Bass, Up to 24 Hours Playback, Wireless, microSD Compatible, Dark Gray | Available at Sanwa Direct Online Store
https://direct.sanwa.co.jp/ItemPage/400-SP125DG

The packaging for the '400-SP125' looks like this.

The contents include the '400-SP125' unit, an instruction manual, and a USB Type-C charging cable.

The dimensions of '400-SP125' are 8cm high x 10.3cm wide x 3.8cm thick.

This is what it looks like when an adult male holds it in his hand.

The weight was 212g.

On the top surface, from left to right, were the power button, Bluetooth button, volume down button, play/pause button, and volume up button. The hole between the play/pause button and the volume up button is the microphone, which also allows for hands-free calls.

Opening the waterproof cap on the side revealed a USB Type-C port for power supply and a microSD card slot. It takes approximately 2 hours to fully charge from zero, and the continuous usage time is 4-5 hours at 100% volume, 10-11 hours at 50% volume, and 24 hours at 20% volume.

Press and hold the speaker's power button for 3 seconds to turn it on and it will automatically enter pairing mode.

Open the Bluetooth settings screen on the device you want to connect and tap '400-SP125DG'.

I have now successfully paired the '400-SP125' with my device.

You can play music from your device through the speaker. Despite its compact size, it delivers a sense of depth and a well-balanced sound from high to low frequencies.

The '400-SP125' comes with a string, so it can be hung up by attaching this string to a hook or similar object.

The '400-SP125' can not only play music from Bluetooth-connected devices, but also play audio stored on a microSD card. Simply insert a microSD card into the slot inside the waterproof cap and power it on, and the stored audio will automatically begin playing. If audio from a Bluetooth-connected device is playing, pressing the power button once will switch the playback source from the Bluetooth device to the microSD card.

The '400-SP125' is IPX7 waterproof, meaning it can withstand being submerged in water for a while, making it suitable for use in the bathroom or swimming pool. To test the waterproof performance of the '400-SP125,' we filled a bathtub with hot water.