Nikon BF-1B Body Cap

The plastic fits snugly with a satisfying click, so I’m not worried about dust sneaking in while the lens sits in my bag. It’s exactly what I needed to protect the mirror and sensor between shoots.

Lost my original cap somewhere in a camera bag black hole, so this one was a no-brainer replacement. It twists on firmly and seals tight enough that I’m not worried about dust getting to the mirror when I switch lenses outdoors.

Snapped it on before a long hike and didn't have to worry about dust getting in while swapping lenses in the field. It fits the F-mount snugly, with no wobble or give, and the release click is reassuringly crisp.