i have 2 at 26x45 inch and both spot lens. have been lucky and not gotten a line lens. though the line is great for making solar ovens and working with solar fryers. i have some small ones credit card size also and one that is 6in x 4in. ive melted aluminum but not harder metals. this new one may be my strongest yet. green power science on youtube is the place for fresnel vids but they recently changed their name. these tv's are getting hard to find here to. a neighbor down the road threw this one out. got some glass magnifiers from it to.