iFilters O-Ring Replacements for Standard 10" Reverse Osmosis Drinking Water

It has an ID of 3.5" and made of nitrile butadiene rubber (Buna-N) for flexibility and resistance to abrasion and tearing. Fits many standard size housings for that use 10" filters, which are used in various applications, such as drinking water purification, whole house, industrial processes, and more.

eBay