First introduced in Tony Hawk's Pro Skater 4, spine transfers send the skater landing down a different ramp while in the air. Some levels have great spots for using this, like the roof of the school from the first game where the drop below gives a significant speed boost. It is also great to use when no other ramps are on the other side, since it can let the player grind the lip of the ramp, which can solve the problem of ramp-landings killing momentum.