The holder can be both rotated and quickly removed. This means the holder can be knocked off the adaptor ring should you catch it in your clothing, for example. This will protect your camera and lens from potential damage.
The holder can be rotated but is locked to the adaptor ring, and cannot be removed from it. You might select this to secure the holder if you're moving around a location to take several shots (though do remove your filters before moving!).
The holder cannot be rotated and is also locked in place, so cannot be removed from adaptor ring. You might select this option to prevent accidentally nudging the holder after you have rotated it for use with Neutral Density Grads.
These can be quickly and easily swapped over using the filter-removal tool supplied. The blocks snap into place and remain secure until the photographer is ready to change them. Up to three filters can be used with today’s wideangle lenses without the risk of vignetting.