Reflex fabric with a 10% polyamide infusion stretches with the most intense activity.
Fabric | ReflexCotton
90% Combed Cotton // 10% Polyamide
Omni Essentials | Black
The stretch on these is solid I can pull on it without feeling like it might snap on me. Sometimes I get stringers with no stitching on the arm straps and it helps with the stretch but also makes it easier to ruin. The threads on these ones don't make them stiff at all the stretch is definitely there!