Made of premium, high-strength, and heat-resistant polymer and stainless steel hardware, this snap-on Front Lens Cap from Bioluminous features locking grips and is specifically designed for the Nikon 500mm f/4 lens. The lens cap features rugged and durable spring-loaded release tabs that are large enough to mount and remove the lens cap while wearing gloves, and the cap offers a snug fit and can be mounted on the lens with or without the lens hood attached.
Measure the front element of the lens to see if you need the 121mm or 125mm diameter version.