New Snap-on plastic lens cap
The lens cap grips the filter thread and is therefore less likely to fall off than a push-on lens cap.
Please note that these caps are not compatible with some filters/cameras. They do not grip onto original Olympus filters or 35RC cameras. They do however fit on all Trip 35 cameras and most other filters, i.e. those filters that have a screw thread in-front of the filter glass.
For the best fit on a Trip, turn the focus to infinity.