"This optical bench apparatus is used for experimenting of how an image is created and how to find the focal length. This apparatus set consists of a bench which is shaped like a rail, in which the scale is written on the sides with length of 90cm.ยฑ1mm. The lens are adjustable. This set includes: 2-faced convex lens with 40mm. in diameter, with a focal length of 100ยฑ2mm. 2-faced convex lens with 30mm. in diameter, with a focal length of 50?2mm. 2-faced convex lens with 30mm. in diameter, with a focal length of 75ยฑ4mm. Linear axis convex lens with 50mm. in diameter, with a focal length of 300ยฑ2mm. A mirror of size 80x120mm, with 1 candlestick. An object sheet with size 70x95mm. A screen with size 80x120mm."