6" Tri Clamp Sight Glass with Temperature Resistant Borosilicate Glass - Perfect for Brewing, Dairy Processing & Pharmaceutical Applications

Very thick sturdy glass that can handle quick pressure changes up to and down from 100PSI with no problem. If you receive this without gaskets as I did, make sure to take the unit completely apart including the metal rods before attempting to pull out the glass. The bottom of the glass was somewhat glued to the bottom piece of this unit. This was only a flimsy coating of some sort that wasn't able to hold vaccuum or pressure well and leaked. With a 4in viton triclamp seal I was able to make a seal even though the glass and bottom of the glass do not have the triclamp grooves, once I received the proper gaskets those were swapped in and did just as good of a job.This is definitely the best bang for your buck. Works very well once you have a good seal and it is adequately squished together against its seal.