Band tension that climbs as your chest closes the rep.
Keep that elbow bend fixed and lead with your hands, do not let it turn into a press.
With the band anchored behind you at chest height, sweeping your arms together in a wide arc gives the chest exactly what a fly is for, tension focused on squeezing the arms across the body. The band ramps up as your hands close, so the finish position, where the pecs are fully shortened, is the hardest inch of the rep, with the front delts assisting the sweep. The fixed soft elbow bend is the contract you sign, the moment the elbows start bending and extending, you are pressing, not flying.
Yes, it is the same arc with a different resistance curve. Cables load the stretch more evenly, the band bites hardest at the squeeze, which many lifters find gives them a chest contraction they never feel on presses. Anchor height and band choice are your progression tools.
Set a soft bend at the start and freeze it there for the whole set. The angle never changes, the movement happens entirely at the shoulders, if the elbows open and close you have drifted into a press and off the chest.
Chest height behind you is the classic mid-chest fly. Anchor higher and sweep down to bias the lower chest, anchor lower and sweep up for the upper fibres, one band, three chest angles.
