Back to back T-spin triple is a difficult maneuver in SRS based games, which in (for example) Tetris DS sends a total of thirteen garbage rows to the opponent. It requires the player to make two T-spin triples back to back.
Setups notched on side
LT/JT, the simplest set up. Its flaw is its heavy dependence on T tetrominoes, which could otherwise be held to complete the T-spin.
Setups involving S and I:
The core of JTTL can be replaced with two S or Z tetrominoes:
Setups notched in center
Setups containing I:
Switching sides
A player may switch sides to clear Back to Back T-spin Triples indefinitely.
Any T-spin line clear is good enough to keep the "Back to Back" alive, which allows for lopsided designs.
These two have interchangeable parts.
See also