[EN] In this work, given a unital Banach algebra A and a \in A such that a has a Moore-Penrose inverse a^+, it will be characterized when a^+ a - a a^+ is invertible. A particular subset of this class of objects wil also be studied. In addition, perturbations of this class of elements will be studied. Finally, the Banach space operator case will also be consider.The third author is supported by Grant No. 174025 of the Ministry of Science, Technology and Development, Republic of Serbia.Benítez López, J.; Boasso, E.; Rakocevic, V. (2015). Co-EP Banach algebra elements. Banach Journal of Mathematical Analysis. 9(1):27-41. doi:10.15352/bjma/09-1-3S27419
