  We study transport properties of an arbitrarily shaped ultraclean graphene
sheet, adiabatically connected to leads,composed by the same material. If the
localized interactions do not destroy chiral symmetry, we show that the
conductance is quantized, since it is dominated by the quasi one-dimensional
leads. As an example, we show that smooth structural deformations of the
graphene plane do not modify the conductance quantization.
