Find a huge variety of Silicone Couplers & Boots you need to finish your project 2020 Chevy/GMC 3.0L Duramax. You can find couplers ranging in size from 2� all the way up to 6� diameter. To meet practically any need, a variety of couplers with straight, hump, reducing, and angled bends from 45 to 90 degrees are available. These couplers are constructed with durable rubber or silicone and are reinforced for greater strength. With high-quality brands like PPE, Vibrant, Mishimoto, and Full Send, you�ll find what you need at XDP.