Using a composite fermion picture, we study the lateral transport between two two-dimensional electron gases, at filling factor 1/2, separated by a potential barrier. In the mean field approximation, composite fermions far from the barrier do not feel a magnetic field while in the barrier region the effective magnetic field is different from zero. This produces a cutoff in the conductance when represented as a function of the thickness and height of the barrier. There is a range of barrier heights for which an incompressible liquid, at $ν=1/3$, exists in the barrier region.

3 pages, latex, 4 figures available upon request from brey@marlene.fmc.uam.es. To appear in Physical Review B (RC) June 15th