The J-Turn works like the U-Turn, but also goes through a Pro-pillar!
The U-turn (from the tunnel extension) guides the ball down one level, but does not allow a longer path on the lower level. This is where the U-turn comes into play and allows the ball to be guided through the Pro columns. This of course also works with offset transparent levels, in which case an additional straight line does not have to be installed.
If you're well-aligned, the opposite way also works. Shooting the ball up using the Gauss cannon. There should be another action stone directly above it, though, because the loss of speed is quite significant. The way up isn't necessarily reliable, though!
The J-turn bridges a height distance of 3.5 height stones.
