SI units recalled in some universal settings (6)

'si units' is the definition.
'teslas' can be an answer for 'units' (tesla is a kind of unit). I am unsure of the 'si' bit.

'recalled in some universal settings' is the wordplay.
'recalled in' says the letters should be written backwards (letters recalled or sent back).
'some' indicates a hidden word (some of the parts of the word are used).
'salset' is hidden in the letters of 'universal settings'.
'salset' backwards is 'TESLAS'.

Can you help me to learn more?