What is the other spare parts of A25 military handset?

Speaker
40mm in diameter, 11mm in thickness, small speaker is used. However its impedance is pretty high at 1000Ω with sensitivity -115+/-3dB. The cone paper is sealed by a water-resistant resin.

Microphone
27mm in diameter, 85mm in thickness with housing, dynamic microphone is used. The impedance is low at 150Ω with sensitivity -59+/-3dB. It is sealed by a transparent film.

Another interesting feature that A25 handset has is that it can reduce surrounding noise to a certain level, the function of a noise canceler.

The speaking side of the microphone (left) and its back phase (right). Both phases with sound receiving holes.

Both, the front, and the back of the microphone have sound input holes. Since the position of the front and the back are opposite, noise is input into both sides, which will cancel each other. The audio will not be canceled since it is only input into the speaking side of the microphone. Theoretically, in an environment with a lot of noise that is input into both sides of the microphone at the same time, the noise will be canceled. However, when voice audio is only input into front side of the microphone, it will not be canceled, and it will also be easy to be picked up.

Connector
The AP-125 is the type of connector used for A25 military handset. It has been used by the US military for a long time. This connector is very easy to connect and disconnect, even operating with thick gloves on.

Curly cord
The cord of the A25 handset also wider than cords used on amateur radios. It seems to be heavily shielded to prevent RF interference. The outside cover is very thick and has a high tolerance against temperature changes and chemical substances. 

Comparing to the curled cord of a speaker microphone a Ham radio (left), the thicker A25 cord (right)

-40 degree to 80 degree high and low temperature test

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