What are these?

Anyone recognize what these are and they're used for?
The larger one has Bay19 SL2 on it. The smaller SL1.
Both have a slit in the top. 

I thought they might be some kind of glue dispensing cap or... Something along those lines.

So, what exactly are they... Do you know?
- chase -

Picture of What are these?
Downunder35m7 months ago

Non return valve.
Usually used for liquids or sometimes air.
We have them on our soda machine pumps to make sure during the cycling no unfiltered air can enter the system.
Some people like to use them on their fish tank setups too to prevent water floing back when the pump fails.

-chase- (author)  Downunder35m7 months ago

ahhh, i see... They're the insides of a check valve. Large check valves.

The larger one is 2" and the smaller just over 1.5" at the flat.

Well... I don't currently have a need for such large check valves but I'll find a use for them. Either would make a seemingly nice water based wood glue dispenser/ spreader cap. A thought anyway.

Thanks for letting me know what they are.


Nope, not inside.
They are just pushed onto a pipe or hose end ;)
In some cases with w locking ring though.