Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What is Mean Free Path, when Vacuum Range is "medium vacuum"?

### Inputs:
table_name: table, columns: ['Vacuum range', 'Pressure in hPa (mbar)', 'Molecules / cm 3', 'Molecules / m 3', 'Mean free path']

### Response:
SELECT Mean free path FROM table WHERE Vacuum range = medium vacuum