The 3 diopter flip is a wet lens containing three macro lenses for different combinations of magnification. It is compatible with the Recsea S95 housing.
The lenses are smaller than the port which will cause vignetting (blackening of the edges) if the camera is not zoomed in half-way. Effectively this lens is designed for a slightly longer subject to lens working distance than the 2-flip diopter. However, since there are 3 diopters, you can get greater magnification.
We dive with our products all the time. Please call the Bluewater Photo team at 310-633-5052 with any questions, or email us at sales@bluewaterphotostore.com