We currently use the APX 8000 Radios with the HMN4103 Speaker Mic. There are limited options when it comes to surveillance pieces for this speaker mic. We have tried both the aftermarket and the original. The Command Tac version of the Motorola RLN6424 is awesome. It provides clear audio and is built solid. There are a few places to buy this but so far we have bought most of them from TwoWayRadioSuppy.com because they consistently seem to have the best pricing.