Technically there is no difference between the two. They are the same exact handle. The only difference is that the 01X handle comes supplied loose with the valve and the 11X comes attached to the valve. The difference has to do with how HYDAC Germany ships their valves. They ship the valves with the handles loose so they can fit more valves in a box and to reduce the chance of damage in shipping over seas or by air. This also applies to 02X and 12X handles and 06X and 16X handles.