Aerator Adaptor Help

[bobbob]

I have a Grohe faucet that is 1/2" NPT and am trying to fit it with a sprayer with an attachment that is 55/64". I have been looking for an aerator adaptor that is 1/2" male NPT x 55/64" female with no luck. Am I missing something? It this rare?

Thanks in advance.

 

[CT-18]

Try a 7/8" I have never seen anything that is 55/64"