The blades on our cars are 26" drivers side and 16" passenger side (assuming you have a right hooker). The Bosch Aerotwin packs listed for the Leon are 24" & 16" and although the they fit, the driver's side leaves a larger area un-wiped at the top of the screen and a larger 'half-moon' at the bottom centre of the screen. It's not a major
problem but I do get a bit of water flowing up the screen from the half moon area which I didn't before I changed the wipers.
The Valeo twin packs are OE sizes.