Tef-Flex Style 112A and 113A Convoluted PTFE Bellows Expansion Joints and Flexible Couplings offer the best combination of low spring-rate flexibility, temperature resistance, and the chemical inert properties of PTFE material. The “Tef-Flex” Style 112A 2-Convolute Flexible Coupling, and Style 113A 3-Convolute Expansion Joint were designed to meet the needs of the HVAC, high-technology, and chemical/petrochemical industries.