The Mets invited outfielder Kirk Nieuwenhuis and catcher Kai Gronauer to major league spring training as non-roster prospects. Neither is on the team’s 40-man roster.

Nieuwenhuis, 23, hit .274 with 18 home runs and 77 RBIs last year combined in Double-A and Triple A. Gronauer, 24, hit .291 with four home runs and 43 RBIs in Single-A.