Is it *just* a PRO-2006 or does it happen to have a DB9 connector on the back and *possibly* something mentioning either OPTOscan or OPTO456 on a sticker someplace? While it may be a longshot that it does have the DB9 connector & something about OPTO456 some place on it, it *is* albeit only a conventional (Non digital capable) one heck of a good scanner. (It's the last of in the line of the RS-2004/2005/2006 "Super Scanners" and there are a whole bunch of interesting `tweaks-n-mods' that it can have done to it that enable many different uses. (I'll admit that I've got *several* of them ranging from a couple `in need of some care' 2004s all the way up to 2006s with OPTO boards and other interesting tweaks and mods. Currently a pair of 2006s reside in my current `radio stack' and while not always in use they still see a fair amount of use even in these days of DTRS and other trunking and digital systems.)
Unfortunately, as kruser has already mentioned your friend won't be able to use it to monitor any of the trunking or digital systems here in CO. But, despite that, your friend will be able to monitor a lot of other things, even some things that most of the newer radios can't. (Though, if it hasn't had any of some of the usual, usually done right out of the box, mods there are some frequency ranges it won't cover. [Someplace around here I still have, I think, a list and instructions for all the `out of the box' mods and if I can't locate them right away I suspect that there a *several* other people who can.])
All in all, even with it's lack of the newer formats, it is still one heck of good fun radio.