In the intake for sea water, I have a strainer surrounded by a 3/3/4" x 4" circular glass "pipe" secured sinside a brass fitting. It workjs well and let's you see what you might have gotten into your engine if you didn't have this device...and to remove any debris that has been filttered out. It works wonderfully and has been in there for years. The glass has not broken..yet..but I want to have a spare in case it does. Anyone have an idea where I might get one?