It is quite simple really. The arm replacement does what it needs, it replaces a lost or damaged floyd rose arm.
In my case I decided to replace the socket (the bit permanently attached to your guitar, which you screw the arm into) as I suspected this is what wrecked my old arm. The socket is included, which is great, but I realised just how difficult it is to properly seat it. I ended up having to block the floyd off and gently tap it home with a rubber mallet. In retrospect it would have been better to take the whole floyd out, although no accidents ensued (phew!).
Once fitted, the new arm sits in nicely and I am finally able to adjust wether I want the arm to stay put or swing down again. The day of installation a whole fancy (for me) new solo got penned and dive-bomb madness is back on the daily play menu!