Where are these from?

Well I started out with 4x2" square tubing,it was ok but a little to high,plus the backs aren't adjustable,so I needed to tilt them back to be comfortable,there is also factory shims between the tracks and seats,you can always remove them or add some for moor play,
Also my car is jacked up in the back like a very bad cartoon,so I tilted my seats back for that reason,they are also low only because I like sitting low,