I have one of the earlier ones that came out, about 2 yrs. old now, will not fit down my 6.5 or 7mm barrels, but does an exellent job of inspecting the chamber area and throat, I think I paid 400.00 for it off the truck, was much cheaper than a good borescope. The you tube video does not do it justice, the picture displayed on the screen of the tool is awesome. If it is out with a 5.5mm head, i may have to just trade up to one.