Not sure if any of you already have one of these things but they are VERY impressive, especially for only $50.
I bought a Lyman borescope couple years ago and they work pretty well but they cost a couple hundred bucks. Was reading, on other forums, how guys were really impressed with the image quality of the Teslong and figured for 50 bucks I'd give one a try so I ordered one from Amazon. They were right, the Teslong borescope has very good image quality, definitely better than the Lyman, and considering they costs considerably less, it's a no brainer over the Lyman. They work on everything .20 cal and larger.