I seen James Condon's review of this tool on youtube. Looked up the price and bought one. All I can say is WOW what a tool. I also had an earlier fiber optic device that you could see what you could see. But this thing takes what you can see to a whole new level. All I can say if you need to look inside things take a look at his review and comparison to the units we were using to this thing. Again WOW