Squeezed these into the scupper holes on my old sit-on-top and the hollow rubber squished down to fit snug with no trimming. The conical shape wedges in tight enough that I don't get water sloshing up through the holes anymore.
Riley★★★★★
These popped right into my sit-on-top scupper holes with no trimming and the hollow rubber squishes down to fit tight. Took on a bit of water crossing the lake and not a drop came up through the holes.
Stella★★★★☆
Wasn't sure the conical shape would seal my scupper holes since they're a bit uneven, but the soft rubber squishes in far enough to stop the water. Only gripe is they take some real thumb pressure to seat fully.