A polyolefin composition comprising: a composition comprising a) 10-40 wt% of a propylene homopolymer, or a copolymer of propylene with ethylene or a CH 2 =CHR α-olefin, where R is a C 2 -C 8 alkyl radical, or a copolymer of propylene with ethylene and said CH 2 =CHR α-olefin, said copolymers containing over 85wt% of propylene, and having a fraction insoluble in xylene at room temperature greater than 80wt%; and b) 60-90wt%of one or more copolymers selected from copolymers of ethylene with propylene, or a CH 2 =CHR α-olefin where R is a C 2 -C 8 alkyl radical, and copolymers of ethylene with propylene and said α-olefin, said copolymers containing ethylene in a quantity lower than 40wt% and having solubility in xylene at room temperature greater than 70wt%; the amounts of (a) and (b) being referred to the total weight of (a) and (b); and an additives package comprising (i) one or more organic phosphites and /or phosphonites; (ii) one or more phenolic antioxidant, consisting of an hindered phenol compound; (iii) at least two HALS having different molecular weight; and optionally (iv) one or more epoxidized fatty acid ester. wherein the ratio (iii)/(ii) is equal to or less than 1; and the weight amount of additives package is from 0.5 to 2wt% referred to the weight of the polyolefin composition. a composition comprising a) 10-40 wt% of a propylene homopolymer, or a copolymer of propylene with ethylene or a CH 2 =CHR α-olefin, where R is a C 2 -C 8 alkyl radical, or a copolymer of propylene with ethylene and said CH 2 =CHR α-olefin, said copolymers containing over 85wt% of propylene, and having a fraction insoluble in xylene at room temperature greater than 80wt%; and b) 60-90wt%of one or more copolymers selected from copolymers of ethylene with propylene, or a CH 2 =CHR α-olefin where R is a C 2 -C 8 alkyl radical, and copolymers of ethylene with propylene and said α-olefin, said copolymers containing ethylene in a quantity lower than 40wt% and having solubility in xylene at room temperature greater than 70wt%; the amounts of (a) and (b) being referred to the total weight of (a) and (b); and a) 10-40 wt% of a propylene homopolymer, or a copolymer of propylene with ethylene or a CH 2 =CHR α-olefin, where R is a C 2 -C 8 alkyl radical, or a copolymer of propylene with ethylene and said CH 2 =CHR α-olefin, said copolymers containing over 85wt% of propylene, and having a fraction insoluble in xylene at room temperature greater than 80wt%; and b) 60-90wt%of one or more copolymers selected from copolymers of ethylene with propylene, or a CH 2 =CHR α-olefin where R is a C 2 -C 8 alkyl radical, and copolymers of ethylene with propylene and said α-olefin, said copolymers containing ethylene in a quantity lower than 40wt% and having solubility in xylene at room temperature greater than 70wt%; an additives package comprising (i) one or more organic phosphites and /or phosphonites; (ii) one or more phenolic antioxidant, consisting of an hindered phenol compound; (iii) at least two HALS having different molecular weight; and optionally (iv) one or more epoxidized fatty acid ester. wherein the ratio (iii)/(ii) is equal to or less than 1; and the weight amount of additives package is from 0.5 to 2wt% referred to the weight of the polyolefin composition. (i) one or more organic phosphites and /or phosphonites; (ii) one or more phenolic antioxidant, consisting of an hindered phenol compound; (iii) at least two HALS having different molecular weight; and optionally (iv) one or more epoxidized fatty acid ester.