alpha-D-Man-(1->3)-[alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-D-GlcNAc + H2O = alpha-D-Man-(1->6)-beta-D-Man-(1->4)-beta-D-GlcNAc-(1->4)-D-GlcNAc + D-mannose — reaction