This article examines the control of tension during weft insertion in rapier and projectile looms. Due to deficiencies in existing brush and double leaf tensioners, IRO AB of Sweden has developed a new tensioner system produced in two versions, the co-axial output tensioner (CAT) for endless filament yarns and the Flex-Brake for spun yarns. The operation of the two systems is described and their performances compared to the brush and double leaf tensioner.