Seat Leon Owner's Manual page 36

Weight group Size class
Group 0 to 10 kg
Group 0+ to 13 kg
Group I 9 to 18 kg
Group II 15 to 25 kg
Group III 22 to 36 kg
IUF: Suitable for forward-facing ISOFIX universal child restraint systems approved for use in this weight group.
IL: It is suitable for certain ISOFIX child restraint systems (CRS) that can be for the specific vehicle, restricted or semi-universal categories. Take the child seat manufacturer's
vehicle list into account.
X: ISOFIX position not suitable for ISOFIX child restraint systems for this weight group or size class.
a) The indication of class according to size corresponds to the authorised bodyweight for the child seat. In child seats with universal or semi-universal approval, the class
according to size is indicated on the ECE approval label. The indication of class according to size is stated on the corresponding child seat.
34
Electrical
a)
equipment
E ISO/R1
E ISO/R1
D ISO/R2
C ISO/R3
D ISO/R2
C ISO/R3
B ISO/F2
B1 ISO/F2X
A ISO/F3
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Safety
Vehicle Isofix positions
Front passenger seat
airbag on airbag off
X IL
X IL
X IL
X IL
X IL
X IL
X IL, IUF
X IL, IUF
X IL, IUF
X IL
X IL
Rear side seat Rear central seat
IL X
IL X
IL X
IL X
IL X
IL X
IL, IUF X
IL, IUF X
IL, IUF X
IL X
IL X