Propylene polymer compositions comprising: A) from 70 wt % to 95 wt %, of a random copolymer of propylene with ethylene, containing from 1.5 wt % to 4.5 wt %, of ethylene derived units, having a content of fraction insoluble in xylene at 25° C. of not less than 93%; B) from 5 wt % to 35 wt %, of a copolymer of propylene with ethylene, containing from 7.0 wt % to 17.0 wt % of ethylene derived units; the sum A+B being 100; wherein the melt flow rate, MFR. (Melt Flow Rate according to ASTM 1238, condition L, i.e. 230° C. and 2.16 kg load) ranges from 40 g/10 min and 130 g/10 min; and wherein the relation (I) is fulfilled: 10