Brother Coverstitch Dual Folding Binder XB3388001Brother Coverstitch Dual Folding Binder XB3388001 (SA231CV). The Dual Function Fold Binder is used to fold 1. 25 inch (32mm) wide bias fabric tape into 0. 31 inch (8mm) wide double fold bias tape and then apply the bias tape binding to the edge of fabric. Attach the binder to the cover stitch machine simply with the two included screws. This accessory may also be used as a binder for single fold bias tape. Compatible with: Brother CV3440 Brother CV3550