A heterophasic polypropylene composition comprising (percent by weight referred to the sum of components A) and B)): A) from 80% to 97% of a random copolymer of propylene containing from 0.1 to 4% of 1-hexene derived units; B) from 3-20% of a copolymer of propylene and ethylene having a content of ethylene derived units ranging from 50% to 55% extremes excluded; wherein the heterophasic polypropylene composition is endowed with a Melt Flow Rate: measured according to ISO 1133 (230° C., 5 Kg) ranging from 0.5 to 5 g/10 min; and an intrinsic viscosity (IV) of the fraction soluble in xylene at room temperature ranging from 2.5 to 5.5.