Speeding Tickets: 21 in 20 School Zone

My question involves a traffic ticket from the state of: WA

School zone ...21 in a 20 ;-(

What are the odds this will stand if contested?

The officer didn't provide any paperwork. No agree to appear either written or verbal. He said I'll see something in the mail.
I don't think he has me on SMD. He got the car in front of me and told me I was "going about the same speed".

I suspect (hope) I won't see anything in the mail.

Question: If no paperwork was shown to me, is this really a citation?

Thanks for you help.

Speeding Tickets: 21 in 20 School Zone