KMC-45D_51D.jpg

These are a couple of Kenwood speaker microphones. I believe both of these maybe discontinued models. You can find these used, and maybe some NOS, new old stock, available on various auction sites. 

The "D" in the model name signifies the microphone has the additional filtering to function properly when used with a DMR type radio. Of course they can be used just fine with an FM only type. The non "D" model type should not be used on DMR, but is fine for regular FM work.

The two-pin plug on the KMC-45D is the Kenwood type "K1." This is very commonly found on most, if not all, of the Chinese radios.

The KMC-51D connector is the Kenwood specific "universal" connector found on many of their higher end radio models.

The KMC-45D is a very simple design employing a speaker element, mic element and a switch. 

https://manuals.repeater-builder.com/Kenwood/kmc/KMC-45_B51-8845-00.pdf

The KMC-51D is a very sophisticated design employing a builtin DSP processing core for noise reduction and audio filtering. There is a KMC-52D which is the same electrical design but has the better IP67 environmental rating. 

https://www.wirelessvoicedata.com/downloads/kenwood/kenwood-kmc-51-52-brochure.pdf

https://manuals.repeater-builder.com/Kenwood/kmc/KMC-51_B53-7014-00.pdf

https://manuals.repeater-builder.com/Kenwood/kmc/KMC-52D_B5B-7122-00.pdf