Like the other two posters, Lezyne. I believe I have the Carbon Road Drive on the road bike and a Mirco Floor drive for the long distance bike.
For the Carbon Road Drive I have the ‘small’, because it’s a backup to a single CO2 cartridge.
The Microfloor drive has only one size, but it’s awesome to set it on the ground or hotel room to pump up tires, has a built in pressure gauge, and it weighs not much more than a full frame pump.