This lens cap is designed specifically for the EF 600mm f/4L lens and protects its front element from dust and scratches when the lens is not in use. Its constructed from strong water-resistant material thats tough yet lightweight. Benefits Protects the EF 600mm f/4L lens when its not in use Protects from moisture, dirt and dust, as well as accidental bumps and scrapes Constructed from robust, water-resistant materials Easy to attach and remove when the pressure is on What\'s in the box E-185C Lens Cap Compatibility EF 600mm f/4L IS III USM EF 600mm f/4L IS II USM RF 600mm F4L IS USM RF 1200mm F8L IS USM