Ace Race Parts 24203 2.000 ID x 4 Long Flex Coupling (Interlock Liner) 304 StainlessAce Race Parts 24203 2. 000" ID x 4" Long Flex Coupling (Interlock Liner) 304 Stainless The Ace Race Parts brand of 100% 304 Stainless Steel Interlock Liner style Flex Couplings are great for reducing vibration and stress in your exhaust system. Ace Race Parts Flex Couplings feature a 304 Stainless braided exterior, a 304 Stainless interlock style internal liner, a flexible 304 Stainless bellow in the center, and 304 Stainless end caps. The interlock