The third iteration of Canon’s powerful 2x Teleconverter, this extender effectively doubles a compatible lens’s focal length, giving you 2x the reach. The extender’s optical coatings retain more image quality from the adapted lens, and resists smudging from fingerprints or grime. The barrel’s environmental sealing keeps up with the sealing from other L series lenses so you don’t have to change lenses if it gets a little wet outside. Just remember you’ll lose one stop of light from your lens with this extender. Compatible with all Canon telephoto lenses 135mm and higher as well as the EF 70-200/2.8L, EF 70-200/2.8L IS, EF 70-200/4L, and EF 100-400/4.5-5.6L zoom lenses.