I think it’s this one
https://www.amazon.com/All-Weather-Mono-Trumpet-Horn-Speaker/dp/B001D0LMG2/ref=mp_s_a_1_3?crid=3KDL1AJ59BMNN&keywords=cb+pa+speaker&qid=1672106987&sprefix=cb+pa+%2Caps%2C83&sr=8-3