Abstract: A polyolefin composition comprising: (A) from 8 to 25% by weight of a crystalline homopolymer or copolymer of propylene: (B) from 75 to 92% by weight of an elastomeric fraction comprising: (1) a first elastomeric copolymer of propylene with from 15 to 32% by weight at least one alpha-olefin of formula H2C?CHR, where R is H or a C2-6 linear or branched alkyl, optionally containing 0.5 to 5% by weight of a diene, said first elastomeric copolymer containing alpha-olefin, and having solubility in xylene at room temperature greater than 50% by weight, the intrinsic viscosity of the xylene soluble fraction ranging from 3.0 to 5.0 dl/g; and (2) a second elastomeric copolymer of propylene with at least one alpha-olefin of formula H2C?CHR, where R is H or a C2-6 linear or branched alkyl, optionally containing 0.