A surface treatment composition comprising a polyfluoropolyether silane having the following general formula: Y-Z a -[(OC 3 F 6) b -(OCF(CF 3)CF 2) c -(OCF 2 CF(CF 3)) d -(OC 2 F 4) e -(CF(CF 3)) f -(OCF 2) g]-(CH 2) h -X-(C n H 2n)-((SiR 2 -O) m -SiR 2) i -(C j H 2j)-Si-(X') 3-z (R 1) z; wherein Z is independently selected from -(CF 2)-, -(CF(CF 3)CF 2 O)-, - (CF 2 CF(CF 3)O)-, -(CF(CF 3)O)-, -(CF(CF 3)CF 2)-, -(CF 2 CF(CF 3))-, and -(CF(CF 3))-; a is an integer from 1 to 200; b, c, d, e, f, and g are integers each independently selected from 0 to 200; h, n and j are integers each independently selected from 0 to 20; i and m are integers each independently selected from 0 to 5; X is a bivalent organic group or an oxygen atom; R is a hydrocarbon group having from 1 to 22 carbon atoms; z is an integer independently selected from 0 to 2; X' is an independently selected hydrolysable group; R 1 is an independently selected hydrocarbon group having from 1 to 22 carbon atoms which is free of aliphatic unsaturation; and Y is selected from F and Si-(X') 3-z (R 1) z (C j H 2j)-((SiR 2 -O) m -SiR 2) i -(C n H 2n)-X-(CH 2) h -; wherein X', z, R 1, j, m, i, n and h are as defined above; provided that when subscript i is 0, subscript j is also 0; when subscript i is an integer greater than 0, subscript j is also an integer greater than 0; and when subscript i is an integer greater than 0, m is also an integer greater than 0; with the proviso that when Y is F; Z is -(CF 2)-; a is an integer from 1 to 3; and subscripts c, d, f and i arc 0; fluorine-containing compounds represented by the general formula below are present in said surface treatment composition in an amount of at least 25 mol % based on the total amount of said surface treatment composition F-(CF 2) a -(OC 3 F 6) b -(OC 2 F 4) e -(OCF 2) g -F; and with the proviso that fluorine-containing compounds represented by the general formula below arc present in said surface treatment composition in an amount of less than 40 mol % based on the total amount of said surface treatment composition Y'-Za-[(OC 3 F 6) b -(OCF(CF 3)CF 2) c -(OCF 2 CF(CF 3)) d - (OC 2 F 4) e -(CF(CF 3)) f -(OCF 2) g]-(CH 2) h -X-(C n' H 2n ')-CR 5 =CR 5 -CH 3; wherein Y' is selected from F and CH 3 -CR 5 =CR 5 -(C n' H 2n')-X-(CH 2) h -; n' is an integer independently selected from 0 to 17; R 5 is independently selected from a hydrogen atom and a methyl group; and Z, a, b, c, d, e, f, g, h and X are as defined above. wherein Z is independently selected from -(CF 2)-, -(CF(CF 3)CF 2 O)-, - (CF 2 CF(CF 3)O)-, -(CF(CF 3)O)-, -(CF(CF 3)CF 2)-, -(CF 2 CF(CF 3))-, and -(CF(CF 3))-; a is an integer from 1 to 200; b, c, d, e, f, and g are integers each independently selected from 0 to 200; h, n and j are integers each independently selected from 0 to 20; i and m are integers each independently selected from 0 to 5; X is a bivalent organic group or an oxygen atom; R is a hydrocarbon group having from 1 to 22 carbon atoms; z is an integer independently selected from 0 to 2; X' is an independently selected hydrolysable group; R 1 is an independently selected hydrocarbon group having from 1 to 22 carbon atoms which is free of aliphatic unsaturation; and Y is selected from F and Si-(X') 3-z (R 1) z (C j H 2j)-((SiR 2 -O) m -SiR 2) i -(C n H 2n)-X-(CH 2) h -; wherein X', z, R 1, j, m, i, n and h are as defined above; provided that when subscript i is 0, subscript j is also 0; when subscript i is an integer greater than 0, subscript j is also an integer greater than 0; and when subscript i is an integer greater than 0, m is also an integer greater than 0; with the proviso that when Y is F; Z is -(CF 2)-; a is an integer from 1 to 3; and subscripts c, d, f and i arc 0; fluorine-containing compounds represented by the general formula below are present in said surface treatment composition in an amount of at least 25 mol % based on the total amount of said surface treatment composition F-(CF 2) a -(OC 3 F 6) b -(OC 2 F 4) e -(OCF 2) g -F; and with the proviso that fluorine-containing compounds represented by the general formula below arc present in said surface treatment composition in an amount of less than 40 mol % based on the total amount of said surface treatment composition Y'-Za-[(OC 3 F 6) b -(OCF(CF 3)CF 2) c -(OCF 2 CF(CF 3)) d - (OC 2 F 4) e -(CF(CF 3)) f -(OCF 2) g]-(CH 2) h -X-(C n' H 2n ')-CR 5 =CR 5 -CH 3; wherein Y' is selected from F and CH 3 -CR 5 =CR 5 -(C n' H 2n')-X-(CH 2) h -; n' is an integer independently selected from 0 to 17; R 5 is independently selected from a hydrogen atom and a methyl group; and Z, a, b, c, d, e, f, g, h and X are as defined above.