Thick outer vinyl sleeves

In the past I bought some sleeves that were 100% crystal clear and very thick: they can even stand straight on its own without a record inside.
Now I cant find them in the market... do you know where I can look for them?
thanks in advance
Are you talking about outer sleeves that cover the album jacket? has them (although I'm not sure they're as thick as you require):
Sleevecity has 5 mil outer sleeves. Yes they can pretty well stand up on their own.
I have several thousand of them.
Only problem is they tend to be slightly different sizes when from different orders. So some will NOT fit over double albums. This is annoying, but I have enough which were bigger so I can swap them.
I do not know if they have 'fixed' this annoying issue with their sleeves or not. Last I ordered some two years ago.
I recently read on another forum that the size issue has been rectified.
thanks for the information. will follow your advice
just bough a package to verify if they are what Im looking for, thanks again.
Mylar record sleeves available at as another option....
thanks, will considered also but they are expensive