Recently it was shown that "λ-Zeeman Technique" (λ-ZT) is a convenient tool to study individual transitions between the Zeeman sublevels of hyperfine levels in an external magnetic field. λ-ZT is based on resonant transmission spectrum of nanometric thin cell (NTC) of thickness L = λ, where λ is the resonant wavelength 794 nm for Rb D1 line. Narrow velocity selective optical pumping (VSOP) resonances in the transmission spectrum of the NTC are split into several components in a magnetic field. Examination of VSOP resonances allows one to identify and investigate an atomic transition in the range of magnetic fields 10 - 5000 G. Here we present a new method for selective addressing of VSOP resonance amplification (more than 10 times).