A propylene polymer composition comprising (percent by weight):A) 65%-85% of a propylene copolymer containing from 2.0% to 5.0% of ethylene derived units having MFR L (Melt Flow Rate according to ASTM 1238, condition L, i.e. 230° C. and 2.16 kg load) from 0.5 to 50 g/10 min and a melting temperature Tm ranging from 146° C. to 155° C.; B) 15%-35%, of a copolymer of ethylene and propylene with from 74% to 87%, of ethylene derived units; the composition having the intrinsic viscosity of the fraction soluble in xylene ranging from 0.8 to 1.2 dl/g preferably from 0.9 to 1.1 dl/g.