Yamaha Silent Brass Mute Only

This is just the mute part of Yamaha's Silent Brass.
It hasn't been used for a while, so I'm not sure if it's still usable, but it attached to the bell without any problems.
It physically covered the bell, so it did reduce the sound. I believe it can be used for practicing at home.
The connecting device (I think it was about the size of a small tablet) that came with the set is lost and is not included.

I haven't tested it by connecting it, so I would like someone who understands this to purchase it.