I am not a fan of those, my Gemini came with one as standard,
but what I found is they are susceptible to foreign objects wedging them open.
I got a concerned call from another boat owner a few years ago
when on a mooring in Cornwall, as my rib had water
lapping over the transom it was sitting that low and all because
the ping pong bailer had been forced open by a small piece of label
from a 2 stroke oil bottle, that must have been floating around.
I took the bailer out, replaced it with a screw in bung, and fitted a second bilge pump!