There are two sizes of Lense On! The 6 inch diameter is the Standard Size for small to medium size cameras. The 7 1/2 inch diameter Professional Size is for the larger, professional cameras. The round shape is easy to use, because there is no front or back when placing your camera on top of it. Each Lense On! platform base comes with an inner bean bag to fill with my special mixture of ground recycled rubber and plastic micro beads.