Genuine original Canon part. BRAND NEW, NEVER BEEN USED. 

This is the front METAL Protection Ring 

It's compatible with these 3 Canon Lens:

EF400mm F4 DO IS II USM, Mark II 

EF 300 mm F2.8L IS II USM Mark II

EF 200-400 mm F4L IS USM Extender 1.4x

If your lens is not in the list, please don't buy it. Or contact me for other choice.