I HAVE ADD9931 RECEIVER. HOW CAN I TELL IF IT ID 288mz versus 318mz? Back panel on protective case has 318FR. IS TJIS 318 frequency? If it is which product will work?

Yours is 318. Allstar has been discontinued. Below is a link to the only receiver still made.

https://www.movingupgaragedoors.com/hive-318-gdo-allstar-9-switch-trinary-318-mhz-one-channel-receiver