Hunter ADM99 ACC Decoder Output Module ACC family controllers may be ordered in decoder versions as complete model numbers. Individual decoder output modules (ADM-99) may also be retrofitted to existing controllers, to convert them to decoder operations. However, decoder and conventional output modules may not be installed in the same controller at the same time. Decoder Output Module, to convert existing ACC99D controllers to decoder operation. The ADM-99 is already included already in the ACC99 versions above. It may be installed in a stock conventional controller, to convert it to decoder operations. It is also used as a replacement component for repair purposes.