The Ashbory bass (made by Fender) is a strange instrument. It's notes are the same as those of a standard bass, but it is the size of a baritone ukulele. This makes it popular with uke players and uke groups who want to fill out their sound.
The most unusual aspect of the Ashbory Bass, even more so than the size, is its strings. Rather than steel strings, it has silicon rubber strings. These act very differently to standard strings and take some getting use to (even more so if you are not used to playing a fretless instrument). They also produce a different sound - closer to an acoustic bass than a standard electric bass.
It should be noted that the bass's G string is notoriously easy to snap. As a result, you can buy whole sets of just G-strings. Before you ask, no, you can't put standard bass strings on an Ashbory. The silicon rubber strings are much lower tension than steel strings.
As you can tell by this video by WS64, the Ashbory bass complements the sound of the ukulele very well.