Cossie will be coming out of storage soon and I've decided I need to pay a bit more heed to security

Was thinking I'd get a disklok, but without having the car to check, I'm not sure what size to get to fit a standard 3dr steering wheel. Any ideas?

small = 35 - 39cm
medium = 39 - 41.5cm
large = 41.5 - 44cm