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

### Instruction:
What's the sSpec number of the processor having an ultra-low power I/O?

### Inputs:
table_name: table, columns: ['Model number', 'sSpec number', 'Cores', 'Frequency', 'Turbo', 'L2 cache', 'L3 cache', 'GPU model', 'GPU frequency', 'Socket', 'I/O bus', 'Release date', 'Part number(s)', 'Release price ( USD )']

### Response:
SELECT sSpec number FROM table WHERE I/O bus = ultra-low power