We've already had the subwoofer vest, but if you want an even more convenient and lightweight strap-on sub, maybe you need Lofelt's Basslet 'watch'.
Designed to let you "feel the music", this silent device works across the low-end frequency spectrum (10 - 250Hz) and promises a truly immersive experience. You simply have to plug the 'sender' unit into your device of choice (phone, tablet, laptop etc), plug your headphones into that and then strap the Basslet to your wrist.
The Basslet is powered by what its developers call the LoSound engine. The technology is based on "an innovative voice-coil design with highly optimised magnetic flows which allows it to be extremely powerful yet remarkably compact".
We're told that the Basslet can run for more than six hours on a single charge at full volume, and that the charging time is less than an hour.
You can find out more on the Basslet Kickstarter page. The €50,000 funding goal has already been reached, and all the super early bird offers are gone, but you can still pledge €129 and get a Basslet in December.