Pacific Northwest Laboratories has the info on their web site. However, their goal was to make a very inexpensive scope using glass beads meant for industrial purpose. With those you have to pick through several to get one that gives a good image but they are very inexpensive. I bought several quality lenses in bulk from china. These cost me about $1 each due to bulk order. Here in USA they cost around from $8 to $40 each. The clip scope is kind of a novelty item that I intended to improve and sell as more useful educational device, but I got busy and dropped the ball.