The Fotodiox PRO EF/EF-S x2.0 is a teleconverter lens that will work with many Canon EF mount lenses. The inscription on the side says it will work with EF-S lenses, but none of the ones we've tried have worked, so you'll have a better time using EF mount only. The teleconverter multiplies the focal length by two times, and will cut the amount of light by two f stops. Optics are clean and there are minimal signs of wear.