Yes, as stated above, it is a coolant filter. Be "gentle" when closing the valve....it, as I recall, is an aluminum setup and can be broken. And don't forget to reopen it when finished....I almost forgot to reopen mine!
BTW, if you are using now or are going to use an Extended Life coolant like Mobil Delvac with OAT formula (organic acid technology) in your ISC, you do not need the supplemental coolant additives (SCA) or the test strips. In that case, per Cummins tech line, you should go with a non SCA-charged filter such as Cummins Fleetguard WF 2077. Delvac, for example, is good for 600,000 miles on-road use before changing......"topping off" should be done with the same or comparable OAT-type coolant.
You might want to contact the Cummins filter folks to discuss.....their customer service people are great!
Hope this helps.....