This is an omni-directional horizontally polarised antenna. Mine was a commercial one made by Wimo, but many make their own. Mine was the 2m version, and to my surprise, it also had a respectable match on 70cm, where it also gets used, although I have no idea of the polar plot on 70cm.
On 2m, it is near omni-directional with a little gain. With 2m FT8, it seems capable of remarkable DX at any time. I think this is because of some form of troposcatter. Even with QRP 2m FT8, this seems to work.
The main advantage is that no rotator is needed. With my kind of 2m operation, this suits me fine. Clearly, if you want SSB DX frequently, a big beam, tower and high power would help!