Primadonna nose pads, available in silicone and pvc materials. 17 mm "D" shape shown here! One specific left and right nose pad. The straight edge of the nose pad is to be mounted away from the face. These nose pads have a distinct mount to them, the base of the nose pad has a "T" shaped mount that looks like a hook on each side of the "T". These are mounted by putting the nose pad in the open slot of the nose pad arm at an angle. So that the hook can lift over the inside edge of the nose pad arm slot. Then press the nose pad in while straightening it, so that it will pop in. Similar to a snap-in nose pad, yet the mount is slimmer in design and will not fit a standard snap-in mount. The sizes range from 9 mm button(round) to a 20 mm assymetrical "D" shaped nose pad. And they are available in silicone and PVC(Vinyl). Silicone is much more flexible and has five sizes, while the pvc material only has four available sizes. Reminder: Always check the mount style of your eyeglass frame before ordering nose pads. It is very important or the nose pad will not fit. As for size and material, that depends on personal preference.