Cash equivalents duration

When is the cash equivalents duration used to alter duration in a portfolio? It usually has a duration of .25

It’s used when you’re adjusting the duration with a fixed-for-floating swap.

The duration of the floating leg is generally calculated as ½ of the time between payments. So, if the swap pays semiannually, the duration of the floating leg would be 0.25 years.

cash is .25 cid