anyone dissect a microbypass yet?

Hey guys, I'm an installer at a local shop, we're a Pioneer, Alpine, Kenwood, Rockford dealer. For the screens since everyone went to double pulse grouding for video bypass and the simple relays don't work anymore, we now have to use PAC Audio TR7 modules for video bypass. These are convenient because we are also an AAMP dealer who owns PAC so we get these fairly cheap and they are easy to order when we are ordering our kits/harnesses etc. And as a plus the TR7's are coming pre-programmed now for double pulse instead of needing to be programmed with the brown wire like they used to. Anyway, that being beside the point of the post. Not out of necessity but out of curiosity I really want to know what is inside the MicroBypass modules internally that allows them to perform double pulse? Here's what I'm talking about: http://www.microbypass.com/index.php?act=viewProd&productid=1 http://www.microbypass.com/index.php?act=viewProd&productid=7 I was thinking a transistor but am only vaguely familiar with the operation of transistors as I've never had to use one before so I'm not sure how they would perform a double pulse if that is what is inside of these guys. Anyone taken one of these guys apart yet and know the answer to this? :)

555 timer