A compound which is a fluoro(poly)ether group-containing silane compound of any of the formulae,,,, or: wherein, each independently at each occurrence: PFPE is -(OC 3 F 6) d - wherein the repeating unit- (OC 3 F 6) - has a branched structure, and d is an integer of 2-200; Rf is C 1-16 -alkyl optionally substituted by F; X 1 is -(R 31)p'-((X b) l') q' -; wherein, each independently at each occurrence, R 31 is a single bond, -(CH 2) s' - optionally substituted by one or more F, or o-, m-, or p-phenylene; s' is an integer of 1-20; X b is -O-, -(OR 35) n4 -, -S-, o-, m- or p-phenylene, -C O-, -Si(R 33) 2 -, -(Si(R 33) 2 O) m' -Si(R 33) 2 -, -CON(R 34)-, -O-CON(R 34)-, -N(R 34)- or -(CH 2) n' -, wherein R 33 is phenyl, a C 1-6 -alkyl or C 1-6 -alkoxy; R 34 is H, phenyl or C 1-6 -alkyl; R 35 is C 1-6 -alkylene; n4 is an integer of 1-5; m' is an integer of 1-100; n' is an integer of 1-20; l' is an integer of 1-10; p' is 0 or 1; q' is 0 or 1; at least one of p' and q' is 1, and the order of therepeating units in parentheses is arbitrary; R 11 is H or halogen; R 12 is H or C 1-20 -alkyl; X 2 is a single bond or a divalent organic group; R 13 is OH or a hydrolyzable group; R 14 is H or C 1-22 -alkyl; n is an integer of 1-3 for each (-SiR 13 n R 14 3- n) unit; t is an integer of 2-10; in the formulae and, there are at least two SiR 13; (Rf-PFPE) β' -X 3 -(SiR a 3) β (R a 3 Si) β -X 3 -PFPE-X 3 -(SiR a 3) β wherein PFPE and Rf are as defined above and, each independently at each occurrence: X 3 is a single bond or a 2- to 10-valent organic group; β is an integer of 1-9; β' is an integer of 1-9; R a is -Z 3 SiR 72 q1 R 73 r1; wherein, each independently at each occurrence, Z 3 is a divalent organic group and does not include a group which forms a siloxane bond together with a Si atom; R 72 is OH or a hydrolyzable group; R 73 is H or C 1-20 -alkyl; q 1 is 2 or 3; r1 is 0 or 1; (q1+r1) = 3 in each (-Z 3 -SiR 72 q1 R 73 r1); Rf-PFPE-X 5 -CR e 3 R e 3 C-X 5 -PFPE-X 5 -CR e 3 wherein PFPE and Rf are as defined above, X 5 is as defined for X 1 in formulae and above and, each independently at each occurrence: R e is -Y-SiR 85 n 2 R 86 3- n 2; Y is a divalent organic group; R 85 is OH or a hydrolyzable group; R 86 is H or C 1-20 -alkyl; and n2 is an integer of 1-3 for each (-Y-SiR 85 n 2 R 86 3- n 2) unit, with the proviso that a compound of the formula wherein x4 = 6 and is a mean value of the number of units, is excluded PFPE is -(OC 3 F 6) d - wherein the repeating unit- (OC 3 F 6) - has a branched structure, and d is an integer of 2-200; Rf is C 1-16 -alkyl optionally substituted by F; X 1 is -(R 31)p'-((X b) l') q' -; wherein, each independently at each occurrence, R 31 is a single bond, -(CH 2) s' - optionally substituted by one or more F, or o-, m-, or p-phenylene; s' is an integer of 1-20; X b is -O-, -(OR 35) n4 -, -S-, o-, m- or p-phenylene, -C O-, -Si(R 33) 2 -, -(Si(R 33) 2 O) m' -Si(R 33) 2 -, -CON(R 34)-, -O-CON(R 34)-, -N(R 34)- or -(CH 2) n' -, wherein R 33 is phenyl, a C 1-6 -alkyl or C 1-6 -alkoxy; R 34 is H, phenyl or C 1-6 -alkyl; R 35 is C 1-6 -alkylene; n4 is an integer of 1-5; m' is an integer of 1-100; n' is an integer of 1-20; l' is an integer of 1-10; p' is 0 or 1; q' is 0 or 1; at least one of p' and q' is 1, and the order of therepeating units in parentheses is arbitrary; R 31 is a single bond, -(CH 2) s' - optionally substituted by one or more F, or o-, m-, or p-phenylene; s' is an integer of 1-20; X b is -O-, -(OR 35) n4 -, -S-, o-, m- or p-phenylene, -C O-, -Si(R 33) 2 -, -(Si(R 33) 2 O) m' -Si(R 33) 2 -, -CON(R 34)-, -O-CON(R 34)-, -N(R 34)- or -(CH 2) n' -, wherein R 33 is phenyl, a C 1-6 -alkyl or C 1-6 -alkoxy; R 34 is H, phenyl or C 1-6 -alkyl; R 35 is C 1-6 -alkylene; n4 is an integer of 1-5; m' is an integer of 1-100; n' is an integer of 1-20; R 33 is phenyl, a C 1-6 -alkyl or C 1-6 -alkoxy; R 34 is H, phenyl or C 1-6 -alkyl; R 35 is C 1-6 -alkylene; n4 is an integer of 1-5; m' is an integer of 1-100; n' is an integer of 1-20; l' is an integer of 1-10; p' is 0 or 1; q' is 0 or 1; R 11 is H or halogen; R 12 is H or C 1-20 -alkyl; X 2 is a single bond or a divalent organic group; R 13 is OH or a hydrolyzable group; R 14 is H or C 1-22 -alkyl; n is an integer of 1-3 for each (-SiR 13 n R 14 3- n) unit; t is an integer of 2-10; in the formulae and, there are at least two SiR 13; (Rf-PFPE) β' -X 3 -(SiR a 3) β (R a 3 Si) β -X 3 -PFPE-X 3 -(SiR a 3) β X 3 is a single bond or a 2- to 10-valent organic group; β is an integer of 1-9; β' is an integer of 1-9; R a is -Z 3 SiR 72 q1 R 73 r1; wherein, each independently at each occurrence, Z 3 is a divalent organic group and does not include a group which forms a siloxane bond together with a Si atom; R 72 is OH or a hydrolyzable group; R 73 is H or C 1-20 -alkyl; q 1 is 2 or 3; r1 is 0 or 1; Z 3 is a divalent organic group and does not include a group which forms a siloxane bond together with a Si atom; R 72 is OH or a hydrolyzable group; R 73 is H or C 1-20 -alkyl; q 1 is 2 or 3; r1 is 0 or 1; R e is -Y-SiR 85 n 2 R 86 3- n 2; Y is a divalent organic group; R 85 is OH or a hydrolyzable group; R 86 is H or C 1-20 -alkyl; and n2 is an integer of 1-3 for each (-Y-SiR 85 n 2 R 86 3- n 2) unit, Y is a divalent organic group; R 85 is OH or a hydrolyzable group; R 86 is H or C 1-20 -alkyl; and n2 is an integer of 1-3 for each (-Y-SiR 85 n 2 R 86 3- n 2) unit,