From Hard Drop  Tetris Wiki
This is an opening created by player Mr. TSpin. STD stands for Single Triple Double which notes how many lines are cleared by the corresponding TSpins. It is efficient in the sense that it does not waste any T's, the rate of success is extremely high, and that it starts the B2B early. It is also a good way to counter Center 4Wide openings.
Contents 
Mr. TSpin's SingleTripleDouble









Mirrored Alternative to Mr TSpin's STD
In the event that you get a late J, consider this:

OSZ in Second Bag
The O, S and Zpieces in the second bag can always be stacked in a way that a TSpin Triple is prepared at the end of the bag. The order of the pieces in the second bag does not matter at all  the stack will always look the same at the beginning of the third bag.




Perfect Clear chance
If Jpiece comes late in the second bag, then the positions of Opiece and Jpiece can be swapped that means the Opiece is used to build the overhang. This results in a 39.29% Perfect Clear chance after 8 cleared lines (3 bags) whereas only a TSpin Single is made in the third bag.





Here are some further patterns to achieve the Perfect Clear. One of those 6 patterns will be applicable for 39.3 % of all third bags.





Nosomi Continuation
Like previously mentioned, the stack will always look the same after 2 placed bags. With this continuation discovered by the player Nosomi, even the third bag can be placed in the same way, whereas a TSpin Single is made in the third bag instead of the usual TSpin Double. The Zpiece stays on hold until the end of the bag and is then used to prepare a DT Cannon. Altogether, the following TSpins are made in the first 5 bags:
Single > Triple > Single > Double > Triple.





Disadvantage of the technique is that you may have to softdrop the Opiece during the third bag; or make a tricky twist to get the Tpiece in place, if the Spiece was already placed: First you rotate by 180 degrees, then you softdrop a row, rotate in an arbitrary direction (the T piece will be kicked) and rotate back in the other direction.






These four 4th bag placements (found by 10Penta) cover every 4th bag:
S<I, O<J 
S<I, J<O 
I<S, O<J 
I<S, J<O 
Avoid the I<S setups if possible.
STSD
First Setup
You can also do an STSD with a 58.3% chance to end with a Perfect Clear after 14 lines.





Here are all solutions. The first 3 may result with a TSpin Double beforehand.





You can also stack the fourth bag this way. The Perfect Clear rate is 96.98% (7 solutions).





Here is a similar setup. However, there is one more dependency: L before O. The Perfect Clear rate is 74.84% (5 solutions).










Second Setup
There is also another way to set up an STSD which could end with up to 100% chance of getting a 14th row Perfect Clear. This setup was discovered by the player CaptainCream.




In the third bag, the S, J, L and I on the 3rd bag can be stacked in one of the following three ways:



If L comes before O on the 4th bag, making the first 4th bag pattern is possible. This pattern has 93.23% chance of Perfect Clear. If T comes first on the 5th bag, the chance increases to 100%. There is also a slight chance that TSpin Double, Tetris and Perfect Clear could be done in the same bag.
16 solutions; 7 are shown (Both TSpin Double and Tetris could be done on the second Perfect Clear pattern). All solutions.







If O comes before L on the 4th bag, making the second 4th bag pattern is possible. This pattern has 76.51% chance of Perfect Clear. All solutions.
8 solutions; 4 shown




If I comes very late and both L and O comes early, making the third 4th bag pattern is possible. This pattern was found by a Japanese Person. This pattern has a 50.95% chance of Perfect Clear. All Solutions
2 solutions


Mr. TSpin Analogon
The left and right parts are swapped, so the TSpin Triple overhang points towards the wall. This opening has the same dependencies as Mr. TSpin's STD in the first bag (must place O before I and Z before L), and in the second bag, the O, S and Z are stacked in the same way. After the execution, the only real difference is that the TSpin Triple overhang points towards the closer wall which will result in different leftovers.
If I piece comes last in first bag, one can also drop it on the wall which allows to stack the TSpin Triple overhang differently.


One can also arrange the pieces like this, which results in a 58.49% chance of Perfect Clear.





Here are two more ways how the second bag can be stacked, if the I piece is placed in its usual spot. Neither method results in a Perfect Clear chance.


To prevent that vertical Lpiece overhang, it is sometimes possible to drop the J piece on the left and use an L piece from the third bag on its place.
See also
 Hachispin  an opener that also starts with a TSpin Single and a TSpin Triple
 Albatross Special  a setup that can result in a TSpin Double Triple Double
 Mini Triple Double  openers that start with a TSpin Mini instead of a TSpin Single
 Single Triple Double  more openers that also start with a TSpin Single
 DoubleYou  an opener which may also result in an STD