And they also could be request to cover by seal, shield, or open. They can be made of stainless steel. So the types are S+R+number. For exampl: SR2.
Certainly, if you need, we can do it with flange. And the types will be S+F+R+number. For example: SFR2.
They are all used very wide. Pls feel assured with the quality, they won't let you down. Thanks.