 of invertible elements of \(K\) are naturally identified as invertible infinitesimals. Being obtained as inverses of “infinitely large” reals (i.e., reals \(r\) satisfying \(\forall n\in \bN (n \lt r) \lor \forall n\in \bN (r \lt -n)\)) the members of \(\In\) are the counterparts in SIA of the infinitesimals of nonstandard analysis.