MP5 SD silencer

[Alias the Jester]

Now this is going to seem to some an easy one , but as I've never owned or have had a mate own an SD MP5 to me its a legit question.

Simply "How does an SD Silencer fit to the main body of the gun ?" Does it use the three lug system , a thread of some kind or some other form of witchcraft :D

I am working on a project for a really compact CQB MP5 and this info would really help .

Cheers
ATJ :D