What are these plumbing things called?
Yea, I know they're a plug, but what's the actual name?

They're a rubber device with a bolt in the middle. When the nut is
tightened on the bolt, the rubber expands to form a tight seal inside
a pipe. I've seen them used for basement floor drains, during
flooding. Also used for temporary plugs in any pipes. I've also seen
them sold for boating. I dont know much about boating, but I assume
they are some sort of plug for the bottom of the boat.

I'm asking this because I cant understand why this method has not been
tried on the BP oil pipe in the ocean. It's a 20 inch pipe, as I saw
on the news. Why cant they make a 20" plug of this type, and their
robots can tighten the nut. Why is this so difficult? Seems that the
BP company workers are all total idiots. They stuck what looks to be
a 6" pipe in the hole. Like what the f__k is that going to do. Sure,
they're getting some of the oil up that pipe, but think about this.
They had to make and install one mile of pipe, and it only solved a
small percentage of the problem. It took them weeks to do this, and
it's not doing much good. Wouldn't it have been easier to take down a
20 inch plug that probably weighs 50 lbs at most, and tighten a nut.
Seems to make much more sense than one mile of pipe that probably
weighs many tons.

Anyhow, what are these plugs called? As soon as I know, I'm going to
find who manufactures them, and see if they can make something to
help. Relying on BP is about the same thing as a doctor putting a
bandage on the finger of someone who just had a heart attack. Since
BP has proven they are completely illiterate, the time has come for
all of us to find a solution. If we keep relying on the idiots from
BP, pretty soon we'll all be affected.