A bottle closure assembly comprising: an integrally molded: cap portion, elongated tether portion, and retaining means portion; the cap portion being molded to reversibly engage and cover a bottle opening, the retaining means portion being molded to irreversibly engage a bottle neck or an upper portion of a bottle, and the elongated tether portion being molded to connect at least one point on the cap portion to at least one point on the retaining means portion; wherein the integrally molded: cap portion, elongated tether portion and retaining means portion are made from a polyethylene composition comprising: 10 to 70 wt% of a first ethylene copolymer having a melt index I 2, of less than 1.0 g/10min; and a density of from 0.920 to 0.960 g/cm 3, as measured according to ASTM D792; and 90 to 30 wt% of a second ethylene copolymer or an ethylene homopolymer; the second ethylene copolymer or the ethylene homopolymer having a melt index I 2, of at least 20 g/10min, as measured according to ASTM D1238 (when conducted at 190°C, using a 2.16 kg weight); and a density higher than the density of the first ethylene copolymer, but less than 0.970 g/cm 3; wherein the ratio (SCB1/SCB2) of the number of short chain branches per thousand carbon atoms in said first ethylene copolymer to the number of short chain branches per thousand carbon atoms in said second ethylene copolymer is greater than 0.5; and wherein the polyethylene composition has a tensile elongation at break of at least 600 percent, a tensile strength at break of at least 20 MPa, and a melt index, I 2, of from 0.1 to 4.0 g/10min. an integrally molded: cap portion, elongated tether portion, and retaining means portion; the cap portion being molded to reversibly engage and cover a bottle opening, the retaining means portion being molded to irreversibly engage a bottle neck or an upper portion of a bottle, and the elongated tether portion being molded to connect at least one point on the cap portion to at least one point on the retaining means portion; wherein the integrally molded: cap portion, elongated tether portion and retaining means portion are made from a polyethylene composition comprising: 10 to 70 wt% of a first ethylene copolymer having a melt index I 2, of less than 1.0 g/10min; and a density of from 0.920 to 0.960 g/cm 3, as measured according to ASTM D792; and 90 to 30 wt% of a second ethylene copolymer or an ethylene homopolymer; the second ethylene copolymer or the ethylene homopolymer having a melt index I 2, of at least 20 g/10min, as measured according to ASTM D1238 (when conducted at 190°C, using a 2.16 kg weight); and a density higher than the density of the first ethylene copolymer, but less than 0.970 g/cm 3; wherein the ratio (SCB1/SCB2) of the number of short chain branches per thousand carbon atoms in said first ethylene copolymer to the number of short chain branches per thousand carbon atoms in said second ethylene copolymer is greater than 0.5; and wherein the polyethylene composition has a tensile elongation at break of at least 600 percent, a tensile strength at break of at least 20 MPa, and a melt index, I 2, of from 0.1 to 4.0 g/10min. 10 to 70 wt% of a first ethylene copolymer having a melt index I 2, of less than 1.0 g/10min; and a density of from 0.920 to 0.960 g/cm 3, as measured according to ASTM D792; and 90 to 30 wt% of a second ethylene copolymer or an ethylene homopolymer; the second ethylene copolymer or the ethylene homopolymer having a melt index I 2, of at least 20 g/10min, as measured according to ASTM D1238 (when conducted at 190°C, using a 2.16 kg weight); and a density higher than the density of the first ethylene copolymer, but less than 0.970 g/cm 3; wherein the ratio (SCB1/SCB2) of the number of short chain branches per thousand carbon atoms in said first ethylene copolymer to the number of short chain branches per thousand carbon atoms in said second ethylene copolymer is greater than 0.5; and wherein the polyethylene composition has a tensile elongation at break of at least 600 percent, a tensile strength at break of at least 20 MPa, and a melt index, I 2, of from 0.1 to 4.0 g/10min.