Sextet

A grouping that consists of six identical tiles. 

Joker tiles are allowed and up to six Joker tiles can be used in this grouping, depending on how the grouping is exposed. 

If the exposure occurs due to claiming a discarded tile the exposure can contain up to five (5) Joker tiles. 

If the exposure occurs due to a player declaring Mah Jongg and exposing all of their tiles, the exposure may contain up to six (6) Joker tiles. 

Only the Flower tile has more than four identical tiles therefore all sextets, except a sextet of Flowers, must contain at least two Joker tiles.