I cant remember where I got it from I just googled it.
And I wouldn't say for 30quid its a waste! it is one of the best mods I've done and the easiest.
Its a very handy thing to have, never have to worry again about passengers leaving the window down by accident or being able to put your windows down for a bit in the summer to cool the inside of the car down from the office window. Or in the morning when I want to start the car up whilst I open the gates, just roll the window down on my way out the back door, lean into the car and start her up. Maybe I'm just lazy but I think its a mod to have for sure.
Dan