This 5 string J bass has seen a lot of different strings on it.
Rounds always worked but always wanted to have flats on it...
Have tried labella FS, FM, thomastik, Daddario chromes, even pyramid... Could never find a set that had the right tension for a 5 string Jazz... (Talking about feel here, not pitch tension)
The other Labellas had too much tension, thomastik too little, chromes not right, pyramids are like cablecar cables...
So when I've seen these recently I thought I should try as they're meant for Jazz and P basses from Olinto. 
So modern approach to vintage sound and look.
And they are great, bare in mind I've put them on for one hour only so far.
Of course they're bright as they're brand new but they feel amazing straight away. Very polished and smooth.
I had to do the setup all over again, as they're different gauges and different tensions...
I've managed to bring them down to (G=1.85mm//E=2mm// low B is 2.2mm ~ish)
They could go even lower if I wanted to, but the tension is good there.
The FS for example had to come up comparatively in order not to buzz, same for the thomastik.
Really recommend these flats for anyone wanting a vintage feel, look and sound but aren't happy with other brands as mentioned above.
They're not for the people looking for bright flats like EB cobalt flats or rotosound flats.
Definitely on the vintage side of flats, but with more definition and clarity and articulation.
And without the floppiness of low tensions / thomastik, or extra light gauges.