A polyethylene copolymer composition comprising: 10 to 70 wt% of a first ethylene copolymer having a melt index I 2 1, of from 0.1 to 10 g/10min; a molecular weight distribution M w /M n, of less than 3.0; and a density of from 0.930 to 0.960 g/cm 3; and 90 to 30 wt% of a second ethylene copolymer having a melt index I 2 2, of less than 50 g/10min; a molecular weight distribution M w /M n, of less than 3.0; and a density higher than the density of the first ethylene copolymer, but less than 0.970 g/cm 3; wherein the density of the second ethylene copolymer is less than 0.031 g/cm 3 higher than the density of the first ethylene copolymer; the melt index, I 2 1 of the first ethylene copolymer is less than the melt index, I 2 2 of second ethylene copolymer; the ratio (SCB1/SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer is greater than 2.0; and wherein the polyethylene copolymer composition has a molecular weight distribution M w /M n, of from 1.8 to 7.0; a density of at least 0.949 g/cm 3; a high load melt index I 21, of at least 200 g/10min; a Z-average molecular weight Mz, of less than 200,000; a melt flow ratio I 21 /I 2, of less than 40; and a stress exponent of less than 1.40; wherein the stress exponent is defined as Log 10 [I 6 /I 2]/Log 10 [6.48/2.16]. 10 to 70 wt% of a first ethylene copolymer having a melt index I 2 1, of from 0.1 to 10 g/10min; a molecular weight distribution M w /M n, of less than 3.0; and a density of from 0.930 to 0.960 g/cm 3; and 90 to 30 wt% of a second ethylene copolymer having a melt index I 2 2, of less than 50 g/10min; a molecular weight distribution M w /M n, of less than 3.0; and a density higher than the density of the first ethylene copolymer, but less than 0.970 g/cm 3; wherein the density of the second ethylene copolymer is less than 0.031 g/cm 3 higher than the density of the first ethylene copolymer; the melt index, I 2 1 of the first ethylene copolymer is less than the melt index, I 2 2 of second ethylene copolymer; the ratio (SCB1/SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer is greater than 2.0; and wherein the polyethylene copolymer composition has a molecular weight distribution M w /M n, of from 1.8 to 7.0; a density of at least 0.949 g/cm 3; a high load melt index I 21, of at least 200 g/10min; a Z-average molecular weight Mz, of less than 200,000; a melt flow ratio I 21 /I 2, of less than 40; and a stress exponent of less than 1.40; wherein the stress exponent is defined as Log 10 [I 6 /I 2]/Log 10 [6.48/2.16]. wherein the density of the second ethylene copolymer is less than 0.031 g/cm 3 higher than the density of the first ethylene copolymer; the melt index, I 2 1 of the first ethylene copolymer is less than the melt index, I 2 2 of second ethylene copolymer; the ratio (SCB1/SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer is greater than 2.0; and wherein the polyethylene copolymer composition has a molecular weight distribution M w /M n, of from 1.8 to 7.0; a density of at least 0.949 g/cm 3; a high load melt index I 21, of at least 200 g/10min; a Z-average molecular weight Mz, of less than 200,000; a melt flow ratio I 21 /I 2, of less than 40; and a stress exponent of less than 1.40; wherein the stress exponent is defined as Log 10 [I 6 /I 2]/Log 10 [6.48/2.16].